Method of performing random access procedure for preventing handover failure and electronic device for performing same method

Abstract

This electronic device may: receive, from a first cell, a handover command indicating handover from the first cell to a second cell (the handover command includes first PRACH configuration information); attempt a first random access of the second cell a plurality of times on the basis of the first PRACH configuration information; when an RAR for each of the attempted first random accesses is not received from the second cell, compare second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information; and when the second PRACH configuration information is different from the first PRACH configuration information, attempt a second random access of the second cell on the basis of the second PRACH configuration information.

Description

Method for performing a random access procedure to prevent handover failure and electronic device performing the same

[0001] Embodiments relate to a method for performing a random access procedure to prevent handover failure and an electronic device for performing the same.

[0002] An electronic device may receive a handover command including physical random access channel (PRACH) configuration information from a source cell (or a source base station). The electronic device may generate a PRACH preamble using the PRACH configuration information in the handover command, and may attempt random access to the target cell by transmitting the PRACH preamble to the target cell (or the target base station). The electronic device may receive a random access response (RAR) from the target cell, and after receiving the RAR, may transmit a handover completion message to the target cell.

[0003] There may be a mismatch between the PRACH configuration information in the handover command and the PRACH configuration information in the SIB (system information block)2 of the target cell. In this case, when the existing electronic device attempts random access to the target cell based on the PRACH configuration information in the handover command, it may not receive a random access response (RAR) from the target cell. If the existing electronic device does not receive an RAR from the target cell, it may attempt random access to the target cell again based on the PRACH configuration information in the handover command, but may not receive an RAR from the target cell again. The existing electronic device may attempt random access multiple times but may not receive an RAR for each attempted random access from the target cell, and the T304 timer may expire, causing the handover of the existing electronic device to fail. This handover failure may result in a radio link failure (RLF) and call drop.

[0004] According to one embodiment, an electronic device may be provided that can prevent handover failure when a RAR is not received for each of multiple attempted random accesses.

[0005] According to one embodiment, an electronic device may include at least one processor including a memory storing instructions and a processing circuit. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to receive a handover command from a first cell, the handover command instructing a handover from the first cell to a second cell, the handover command including first PRACH configuration information. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to attempt a first random access to the second cell multiple times based on the first PRACH configuration information. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to compare the first PRACH configuration information with second PRACH configuration information in a system information message of the second cell if the electronic device fails to receive an RAR for each of the attempted first random accesses from the second cell. The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to attempt a second random access to the second cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information.

[0006] According to one embodiment, an electronic device may include at least one processor including a memory storing instructions and a processing circuit. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform an operation of receiving a handover command from a first cell, the handover command including first PRACH configuration information, for instructing a handover from the first cell to a second cell. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform an operation of determining whether an identifier of the second cell is included in a table in which information used for random access of a successful handover of the electronic device is recorded. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform an operation of attempting a first random access to the second cell multiple times based on the first PRACH configuration information if the identifier is determined not to be in the table. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to compare the second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information if the electronic device fails to receive an RAR for each of the attempted first random accesses from the second cell. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to attempt a second random access to the second cell based on the second PRACH configuration information if the second PRACH configuration information is different from the first PRACH configuration information.

[0007] According to one embodiment, an operating method of an electronic device may include an operation of receiving a handover command from a first cell, the handover command instructing a handover from the first cell to a second cell (the handover command may include first PRACH configuration information), an operation of attempting a first random access to the second cell multiple times based on the first PRACH configuration information, an operation of comparing second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information when an RAR for each of the attempted first random accesses is not received from the second cell, and an operation of attempting a second random access to the second cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information.

[0008] According to one embodiment, a non-transitory computer-readable recording medium may store a computer program relating to a method of operating an electronic device. The method may include: receiving a handover command from a first cell, which instructs a handover from the first cell to a second cell (the handover command may include first PRACH configuration information); attempting a first random access to the second cell multiple times based on the first PRACH configuration information; comparing second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information when an RAR for each of the attempted first random accesses is not received from the second cell; and attempting a second random access to the second cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information.

[0009] According to one embodiment, a non-transitory computer-readable recording medium may store a computer program relating to a method of operating an electronic device. The method may include: receiving a handover command from a first cell, the handover command including first PRACH configuration information, for instructing a handover from the first cell to a second cell; determining whether an identifier of the second cell exists in a table in which information used for random access of a successful handover of the electronic device is recorded; attempting a first random access to the second cell multiple times based on the first PRACH configuration information when the identifier is determined not to be in the table; comparing second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information when an RAR for each of the attempted first random accesses is not received from the second cell; and attempting a second random access to the second cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information.

[0010] FIG. 1 illustrates a block diagram of an electronic device within a network environment according to one embodiment.

[0011] FIG. 2 is a block diagram of an electronic device in a network environment including multiple cellular networks according to one embodiment.

[0012] FIG. 3 is a flowchart illustrating an example of handover of an electronic device according to one embodiment.

[0013] FIGS. 4 and 5 are diagrams illustrating an example of an operation of an electronic device storing PRACH configuration information in a first table after a handover failure according to one embodiment.

[0014] FIGS. 6 and 7 are diagrams illustrating an example of an operation of an electronic device according to one embodiment of the present invention to store PRACH configuration information in a second table after a successful handover.

[0015] FIG. 8 is a flowchart illustrating an example of the operation of an electronic device according to one embodiment.

[0016] FIGS. 9, 10, and 11 are flowcharts illustrating examples of the operation of an electronic device according to one embodiment.

[0017] FIGS. 12, 13, and 14 are flowcharts illustrating examples of the operation of an electronic device according to one embodiment.

[0018] FIGS. 15 and 16 are drawings illustrating examples of the operation of an electronic device according to one embodiment.

[0019] FIG. 17 is a block diagram illustrating an example of a configuration of an electronic device according to one embodiment.

[0020] FIG. 18 is a flowchart illustrating an example of a method of operating an electronic device according to one embodiment.

[0021] Hereinafter, embodiments will be described in detail with reference to the attached drawings. In the description with reference to the attached drawings, identical components are assigned the same reference numerals regardless of the drawing numbers, and redundant descriptions thereof will be omitted.

[0022] FIG. 1 is a block diagram of an electronic device (101) within a network environment (100) according to an embodiment. Referring to FIG. 1, in the network environment (100), the electronic device (101) may communicate with the electronic device (102) via a first network (198) (e.g., a short-range wireless communication network), or may communicate with at least one of the electronic device (104) and the server (108) via a second network (199) (e.g., a long-range wireless communication network). According to an embodiment, the electronic device (101) may communicate with the electronic device (104) via the server (108). According to one embodiment, the electronic device (101) may include a processor (120), a memory (130), an input module (150), an audio output module (155), a display module (160), an audio module (170), a sensor module (176), an interface (177), a connection terminal (178), a haptic module (179), a camera module (180), a power management module (188), a battery (189), a communication module (190), a subscriber identification module (196), or an antenna module (197). In some embodiments, the electronic device (101) may omit at least one of these components (e.g., the connection terminal (178)), or may have one or more other components added. In some embodiments, some of these components (e.g., the sensor module (176), the camera module (180), or the antenna module (197)) may be integrated into one component (e.g., the display module (160)).

[0023] The processor (120) may control at least one other component (e.g., a hardware or software component) of the electronic device (101) connected to the processor (120) by executing, for example, software (e.g., a program (140)), and may perform various data processing or calculations. According to one embodiment, as at least a part of the data processing or calculation, the processor (120) may store a command or data received from another component (e.g., a sensor module (176) or a communication module (190)) in a volatile memory (132), process the command or data stored in the volatile memory (132), and store the resulting data in a non-volatile memory (134). According to one embodiment, the processor (120) may include a main processor (121) (e.g., a central processing unit or an application processor) or a secondary processor (123) (e.g., a graphics processing unit, a neural processing unit (NPU), an image signal processor, a sensor hub processor, or a communication processor) that can operate independently or together therewith. For example, if the electronic device (101) includes a main processor (121) and a secondary processor (123), the secondary processor (123) may be configured to use less power than the main processor (121) or to be specialized for a specified function. The secondary processor (123) may be implemented separately from the main processor (121) or as a part thereof.

[0024] The auxiliary processor (123) may control at least a portion of functions or states associated with at least one component (e.g., a display module (160), a sensor module (176), or a communication module (190)) of the electronic device (101), for example, on behalf of the main processor (121) while the main processor (121) is in an inactive (e.g., sleep) state, or together with the main processor (121) while the main processor (121) is in an active (e.g., application execution) state. In one embodiment, the auxiliary processor (123) (e.g., an image signal processor or a communication processor) may be implemented as a part of another functionally related component (e.g., a camera module (180) or a communication module (190)). In one embodiment, the auxiliary processor (123) (e.g., a neural network processing unit) may include a hardware structure specialized for processing artificial intelligence models. The artificial intelligence models may be generated through machine learning. This learning can be performed, for example, on the electronic device (101) itself where the artificial intelligence model is executed, or can be performed through a separate server (e.g., server (108)). The learning algorithm can include, for example, supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning, but is not limited to the examples described above. The artificial intelligence model can include multiple artificial neural network layers.The artificial neural network may be one of a deep neural network (DNN), a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted Boltzmann machine (RBM), a deep belief network (DBN), a bidirectional recurrent deep neural network (BRDNN), a deep Q-network, or a combination of two or more of the above, but is not limited to the examples described above. In addition to, or alternatively to, a hardware structure, an artificial intelligence model may include a software structure.

[0025] The memory (130) can store various data used by at least one component (e.g., processor (120) or sensor module (176)) of the electronic device (101). The data can include, for example, software (e.g., program (140)) and input data or output data for commands related thereto. The memory (130) can include volatile memory (132) or non-volatile memory (134).

[0026] The program (140) may be stored as software in the memory (130) and may include, for example, an operating system (142), middleware (144), or an application (146).

[0027] The input module (150) can receive commands or data to be used in a component of the electronic device (101) (e.g., a processor (120)) from an external source (e.g., a user) of the electronic device (101). The input module (150) can include, for example, a microphone, a mouse, a keyboard, a key (e.g., a button), or a digital pen (e.g., a stylus pen).

[0028] The audio output module (155) can output audio signals to the outside of the electronic device (101). The audio output module (155) can include, for example, a speaker or a receiver. The speaker can be used for general purposes, such as multimedia playback or recording playback. The receiver can be used to receive incoming calls. In one embodiment, the receiver can be implemented separately from the speaker or as part of the speaker.

[0029] The display module (160) can visually provide information to an external party (e.g., a user) of the electronic device (101). The display module (160) may include, for example, a display, a holographic device, or a projector, and a control circuit for controlling the device. According to one embodiment, the display module (160) may include a touch sensor configured to detect a touch, or a pressure sensor configured to measure the intensity of a force generated by the touch. The display module (160) may be implemented with an illustrative foldable structure and / or a rollable structure. For example, the size of the display screen of the display module (160) may be reduced when folded, and may be expanded when unfolded.

[0030] The audio module (170) can convert sound into an electrical signal, or vice versa, convert an electrical signal into sound. In one embodiment, the audio module (170) can acquire sound through the input module (150), output sound through the sound output module (155), or an external electronic device (e.g., electronic device (102)) (e.g., speaker or headphone) directly or wirelessly connected to the electronic device (101).

[0031] The sensor module (176) can detect the operating status (e.g., power or temperature) of the electronic device (101) or the external environmental status (e.g., user status) and generate an electrical signal or data value corresponding to the detected status. According to one embodiment, the sensor module (176) can include, for example, a gesture sensor, a gyro sensor, a barometric pressure sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an IR (infrared) sensor, a biometric sensor, a temperature sensor, a humidity sensor, or an illuminance sensor.

[0032] The interface (177) may support one or more designated protocols that may be used to directly or wirelessly connect the electronic device (101) to an external electronic device (e.g., the electronic device (102)). In one embodiment, the interface (177) may include, for example, a high definition multimedia interface (HDMI), a universal serial bus (USB) interface, an SD card interface, or an audio interface.

[0033] The connection terminal (178) may include a connector through which the electronic device (101) may be physically connected to an external electronic device (e.g., electronic device (102)). In one embodiment, the connection terminal (178) may include, for example, an HDMI connector, a USB connector, an SD card connector, or an audio connector (e.g., a headphone connector).

[0034] A haptic module (179) can convert electrical signals into mechanical stimuli (e.g., vibration or movement) or electrical stimuli that a user can perceive through tactile or kinesthetic sensations. In one embodiment, the haptic module (179) may include, for example, a motor, a piezoelectric element, or an electrical stimulation device.

[0035] The camera module (180) can capture still images and videos. In one embodiment, the camera module (180) may include one or more lenses, image sensors, image signal processors, or flashes.

[0036] The power management module (188) can manage the power supplied to the electronic device (101). According to one embodiment, the power management module (188) can be implemented as, for example, at least a part of a power management integrated circuit (PMIC).

[0037] A battery (189) may power at least one component of the electronic device (101). In one embodiment, the battery (189) may include, for example, a non-rechargeable primary battery, a rechargeable secondary battery, or a fuel cell.

[0038] The communication module (190) may support the establishment of a direct (e.g., wired) communication channel or a wireless communication channel between the electronic device (101) and an external electronic device (e.g., electronic device (102), electronic device (104), or server (108)), and the performance of communication through the established communication channel. The communication module (190) may operate independently from the processor (120) (e.g., application processor) and may include one or more communication processors that support direct (e.g., wired) communication or wireless communication. According to one embodiment, the communication module (190) may include a wireless communication module (192) (e.g., a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module (194) (e.g., a local area network (LAN) communication module, or a power line communication module). Among these communication modules, the corresponding communication module can communicate with an external electronic device (104) via a first network (198) (e.g., a short-range communication network such as Bluetooth, wireless fidelity (WiFi) direct, or infrared data association (IrDA)) or a second network (199) (e.g., a long-range communication network such as a legacy cellular network, a 5G network, a next-generation communication network, the Internet, or a computer network (e.g., a LAN or WAN)). These various types of communication modules can be integrated into a single component (e.g., a single chip) or implemented as multiple separate components (e.g., multiple chips). The wireless communication module (192) can verify or authenticate the electronic device (101) within a communication network such as the first network (198) or the second network (199) by using subscriber information (e.g., an international mobile subscriber identity (IMSI)) stored in the subscriber identification module (196).

[0039] The wireless communication module (192) can support 5G networks and next-generation communication technologies following the 4G network, such as NR access technology (new radio access technology). The NR access technology can support high-speed transmission of high-capacity data (eMBB (enhanced mobile broadband)), minimization of terminal power and connection of multiple terminals (mMTC (massive machine type communications)), or high reliability and low latency (URLLC (ultra-reliable and low-latency communications)). The wireless communication module (192) can support, for example, a high-frequency band (e.g., mmWave band) to achieve a high data transmission rate. The wireless communication module (192) can support various technologies for securing performance in a high-frequency band, such as beamforming, massive multiple-input and multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, or large scale antenna. The wireless communication module (192) can support various requirements specified in the electronic device (101), an external electronic device (e.g., the electronic device (104)), or a network system (e.g., the second network (199)). According to one embodiment, the wireless communication module (192) can support a peak data rate (e.g., 20 Gbps or more) for eMBB realization, a loss coverage (e.g., 164 dB or less) for mMTC realization, or a U-plane latency (e.g., 0.5 ms or less for downlink (DL) and uplink (UL), or 1 ms or less for round trip) for URLLC realization.

[0040] The antenna module (197) can transmit or receive signals or power to or from an external device (e.g., an external electronic device). In one embodiment, the antenna module (197) may include an antenna including a radiator formed of a conductor or a conductive pattern formed on a substrate (e.g., a PCB). In one embodiment, the antenna module (197) may include a plurality of antennas (e.g., an array antenna). In this case, at least one antenna suitable for a communication method used in a communication network, such as the first network (198) or the second network (199), may be selected from the plurality of antennas, for example, by the communication module (190). A signal or power may be transmitted or received between the communication module (190) and an external electronic device via the at least one selected antenna. In some embodiments, in addition to the radiator, another component (e.g., a radio frequency integrated circuit (RFIC)) may be additionally formed as a part of the antenna module (197).

[0041] According to various embodiments, the antenna module (197) may form a mmWave antenna module. According to one embodiment, the mmWave antenna module may include a printed circuit board, an RFIC disposed on or adjacent to a first side (e.g., a bottom side) of the printed circuit board and capable of supporting a designated high-frequency band (e.g., a mmWave band), and a plurality of antennas (e.g., an array antenna) disposed on or adjacent to a second side (e.g., a top side or a side side) of the printed circuit board and capable of transmitting or receiving signals in the designated high-frequency band.

[0042] At least some of the above components can be interconnected and exchange signals (e.g., commands or data) with each other via a communication method between peripheral devices (e.g., a bus, GPIO (general purpose input and output), SPI (serial peripheral interface), or MIPI (mobile industry processor interface)).

[0043] According to one embodiment, commands or data may be transmitted or received between the electronic device (101) and an external electronic device (104) via a server (108) connected to a second network (199). Each of the external electronic devices (102 or 104) may be the same or a different type of device as the electronic device (101). According to one embodiment, all or part of the operations executed in the electronic device (101) may be executed in one or more of the external electronic devices (102, 104, or 108). For example, when the electronic device (101) is to perform a certain function or service automatically or in response to a request from a user or another device, the electronic device (101) may, instead of or in addition to executing the function or service itself, request one or more external electronic devices to perform the function or at least a part of the service. One or more external electronic devices that receive the request may execute at least a portion of the requested function or service, or an additional function or service related to the request, and transmit the result of the execution to the electronic device (101). The electronic device (101) may process the result as is or additionally and provide it as at least a portion of a response to the request. For this purpose, cloud computing, distributed computing, mobile edge computing (MEC), or client-server computing technology may be used, for example. The electronic device (101) may provide an ultra-low latency service by using distributed computing or mobile edge computing, for example. In another embodiment, the external electronic device (104) may include an Internet of Things (IoT) device. The server (108) may be an intelligent server utilizing machine learning and / or a neural network. According to one embodiment, the external electronic device (104) or the server (108) may be included in the second network (199).The electronic device (101) can be applied to intelligent services (e.g., smart home, smart city, smart car, or healthcare) based on 5G communication technology and IoT-related technology.

[0044] Electronic devices according to the various embodiments disclosed in this document may take various forms. Electronic devices may include, for example, portable communication devices (e.g., smartphones), computer devices, portable multimedia devices, portable medical devices, cameras, wearable devices, or home appliances. Electronic devices according to the embodiments of this document are not limited to the aforementioned devices.

[0045] The various embodiments of this document and the terminology used therein are not intended to limit the technical features described in this document to specific embodiments, but should be understood to include various modifications, equivalents, or substitutes of the embodiments. In connection with the description of the drawings, similar reference numerals may be used for similar or related components. The singular form of a noun corresponding to an item may include one or more of the items, unless the context clearly indicates otherwise. In this document, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" can include any one of the items listed together in the corresponding phrase among those phrases, or all possible combinations thereof. Terms such as "first," "second," or "first" or "second" may be used merely to distinguish one component from another, and do not limit the components in any other respect (e.g., importance or order). When a component (e.g., a first component) is referred to as "coupled" or "connected" to another component (e.g., a second component), with or without the terms "functionally" or "communicatively," it means that the component can be connected to the other component directly (e.g., wired), wirelessly, or through a third component.

[0046] The term "module" used in various embodiments of this document may include a unit implemented in hardware, software, or firmware, and may be used interchangeably with terms such as logic, logic block, component, or circuit. A module may be an integral component, or a minimum unit or part of such a component that performs one or more functions. For example, according to one embodiment, a module may be implemented in the form of an application-specific integrated circuit (ASIC).

[0047] Various embodiments of the present document may be implemented as software (e.g., a program (140)) including one or more instructions stored in a storage medium (e.g., an internal memory (136) or an external memory (138)) readable by a machine (e.g., an electronic device (101) of FIG. 1). For example, a processor (e.g., a processor (120)) of the machine (e.g., an electronic device (101)) may call at least one instruction among the one or more instructions stored from the storage medium and execute it. This enables the machine to operate to perform at least one function according to the at least one called instruction. The one or more instructions may include code generated by a compiler or code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Here, 'non-transitory' simply means that the storage medium is a tangible device and does not contain signals (e.g., electromagnetic waves), and the term does not distinguish between cases where data is stored semi-permanently or temporarily on the storage medium.

[0048] According to one embodiment, the method according to various embodiments disclosed in the present document may be provided as included in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., Play Store™) or directly between two user devices (e.g., smart phones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily generated in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0049] According to various embodiments, each component (e.g., a module or a program) of the above-described components may include one or more entities, and some of the entities may be separated and placed in other components. According to various embodiments, one or more components or operations of the aforementioned components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., a module or a program) may be integrated into a single component. In such a case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. According to various embodiments, the operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0050] FIG. 2 is a block diagram of an electronic device (201) in a network environment (200) including multiple cellular networks according to one embodiment.

[0051] Referring to FIG. 2, an electronic device (201) (e.g., the electronic device (101) of FIG. 1) may include a processor (210) (e.g., the processor (120) of FIG. 1 or a communication processor), a first-first radio frequency integrated circuit (RFIC) (222-1), a first-second RFIC (222-2), a second RFIC (224), a first radio frequency front end (RFFE) (232), a second RFFE (234), a first antenna module (242), a second antenna module (244), and a third antenna module (246). According to an embodiment, the first-first RFIC (222-1) and the first-second RFIC (222-2) may be implemented as one RFIC (222). The second network (199) may include a first cellular network (292) (e.g., a legacy network) and a second cellular network (294) (e.g., a 5G network). The electronic device (201) may further include at least one component among those described in FIG. 1 , and the second network (199) may further include at least one other network. In one embodiment, the second RFIC (224) may be omitted or included as part of the third RFIC (226).

[0052] According to one embodiment, the first RFIC (222-1), the first RFIC (222-2), the second RFIC (224), the first RFFE (232), and the second RFFE (234) of FIG. 2 may be included in the communication module (190) of FIG. 1 (e.g., the wireless communication module (192)), and the first antenna module (242), the second antenna module (244), and the third antenna module (246) of FIG. 2 may be included in the antenna module (197) of FIG. 1.

[0053] According to one embodiment, the processor (210) may support establishment of a communication channel in a band to be used for wireless communication with a first cellular network (292), and legacy network communication through the established communication channel. The first cellular network (292) may be, for example, a legacy network including a second generation (2G), 3G, 4G, or long term evolution (LTE) network. The processor (210) may support establishment of a communication channel corresponding to a first band (e.g., about 6 GHz to about 60 GHz) (or a frequency range (FR)2 of the 5G standard (e.g., 24.25 GHz to 52.6 GHz)) among the bands to be used for wireless communication with a second cellular network (294), and 5G network communication through the established communication channel. The second cellular network (294) may be a 5G network defined by 3GPP. The processor (210) can establish a communication channel corresponding to a second band (e.g., about 6 GHz or less) (or FR1 of the 5G standard (e.g., 410 MHz to 7.125 GHz)) among the bands to be used for wireless communication with the second cellular network (294), and support 5G network communication through the established communication channel.

[0054] According to one embodiment, the first RFIC (222-1) (or the first RFIC (222)) may, upon transmission, convert a baseband signal generated by the processor (210) into a radio frequency (RF) signal of a frequency band (e.g., about 700 MHz to about 3 GHz) used in the first cellular network (292). Upon reception, the RF signal may be received or acquired from the first cellular network (292) via the first antenna module (242) and preprocessed via the first RFFE (232). The first RFIC (222-1) (or the first RFIC (222)) may convert the preprocessed RF signal into a baseband signal so that it may be processed by the processor (210).

[0055] According to one embodiment, the 1-2 RFIC (222-2) (or the 1st RFIC (222)) may, upon transmission, convert a baseband signal generated by the processor (210) into an RF signal (hereinafter, a 5G Sub6 RF signal) of a Sub6 band (e.g., about 6 GHz or less) used in the second cellular network (294). Upon reception, the 5G Sub6 RF signal may be received or acquired from the second cellular network (294) via the second antenna module (244) and preprocessed via the second RFFE (234). The 1-2 RFIC (222-2) (or the 1st RFIC (222)) may convert the preprocessed 5G Sub6 RF signal into a baseband signal so that it can be processed by the processor (210).

[0056] According to one embodiment, the third RFIC (226) may convert the baseband signal generated by the processor (210) into an RF signal (hereinafter, 5G Above6 RF signal) of a 5G Above6 band (e.g., about 6 GHz to about 60 GHz) to be used in the second cellular network (294). Upon reception, the 5G Above6 RF signal may be received or acquired from the second cellular network (294) via the third antenna module (246) (e.g., antenna (248)) and preprocessed via the third RFFE (236). The third RFIC (226) may convert the preprocessed 5G Above6 RF signal into a baseband signal so that it can be processed by the processor (210). According to one embodiment, the third RFFE (236) may be formed as a part of the third RFIC (226).

[0057] According to one embodiment, the electronic device (201) may include a second RFIC (224) separately from or at least as a part of the third RFIC (226). In this case, the second RFIC (224) may convert a baseband signal generated by the processor (210) into an RF signal (hereinafter, referred to as an IF signal) of an intermediate frequency band (e.g., about 9 GHz to about 11 GHz) and transmit the IF signal to the third RFIC (226). The third RFIC (226) may convert the IF signal into a 5G Above6 RF signal. Upon reception, the 5G Above6 RF signal may be received or acquired from the second cellular network (294) via the third antenna module (246) (e.g., antenna (248)) and converted into an IF signal by the third RFIC (226). The second RFIC (224) can convert the IF signal into a baseband signal so that the processor (210) can process it.

[0058] According to one embodiment, at least one antenna module of the first antenna module (242) or the second antenna module (244) may be omitted or combined with another antenna module to process RF signals of a corresponding plurality of bands.

[0059] According to one embodiment, the third RFIC (226) and the antenna (248) may be disposed on the same substrate to form a third antenna module (246). For example, the processor (120) may be disposed on a first substrate (e.g., main PCB). In this case, the third RFIC (226) may be disposed on a portion (e.g., bottom surface) of a second substrate (e.g., sub PCB) separate from the first substrate, and the antenna (248) may be disposed on another portion (e.g., top surface) of the second substrate (e.g., sub PCB), thereby forming the third antenna module (246). By disposing the third RFIC (226) and the antenna (248) on the same substrate, it is possible to reduce the length of the transmission line therebetween. This can reduce, for example, the loss (e.g., attenuation) of signals in the high-frequency band (e.g., about 6 GHz to about 60 GHz) used in 5G network communications due to transmission line transmission. As a result, the electronic device (201) can improve the quality or speed of communication with the second cellular network (294) (e.g., the 5G network).

[0060] According to one embodiment, the antenna (248) may be formed as an antenna array including a plurality of antenna elements that may be used for beamforming. In this case, the third RFIC (226) may include a plurality of phase shifters (238) corresponding to the plurality of antenna elements, for example, as part of the third RFFE (236). Upon transmission, each of the plurality of phase shifters (238) may shift the phase of a 5G Above6 RF signal to be transmitted to an external source (e.g., a base station of a 5G network) of the electronic device (201) via its corresponding antenna element. Upon reception, each of the plurality of phase shifters (238) may shift the phase of a 5G Above6 RF signal received from an external source (e.g., a base station of a 5G network) via its corresponding antenna element to the same or substantially the same phase. This enables transmission or reception via beamforming between the electronic device (201) and the external source.

[0061] The second cellular network (294) may operate independently of the first cellular network (292) (e.g., Stand-Alone (SA)) or may be connected to it (e.g., Non-Stand Alone (NSA)). For example, a 5G network may only have an access network (e.g., a 5G radio access network (RAN) or next generation RAN (NG RAN)) and no core network (e.g., next generation core (NGC)). In this case, the electronic device (201) may access an external network (e.g., the Internet) under the control of a core network (e.g., evolved packet core (EPC)) of a legacy network after accessing the access network of the 5G network. Protocol information for communication with the legacy network (e.g., LTE protocol information) or protocol information for communication with the 5G network (e.g., New Radio (NR) protocol information) may be stored in a memory (e.g., memory (130) of FIG. 1) and accessed by the processor (210).

[0062] FIG. 3 is a flowchart illustrating an example of handover of an electronic device according to one embodiment.

[0063] Referring to FIG. 3, in operation 311, an electronic device (301) according to an embodiment (e.g., electronic device (101) of FIG. 1, electronic device (201) of FIG. 2) may transmit a measurement report to a source cell (or source base station) (303). The measurement report may include, for example, signal strength of the source cell (303) and signal strength of an adjacent cell of the source cell (303). The source cell (303) may represent, for example, a cell serving the electronic device (301).

[0064] The source cell (303) can determine whether the electronic device (301) will perform a handover (HO) to an adjacent cell based on the measurement report of the electronic device (301). If the source cell (303) decides to perform a HO of the electronic device (301), it can transmit a HO request to a target cell (or target base station) (305) in operation 313. The target cell (305) can, for example, indicate a new cell that will serve the electronic device (301).

[0065] According to an embodiment, the frequency band supported by the target cell (305) may be the same as the frequency band supported by the source cell (303). For example, the EARFCN (E-UTRA absolute radio frequency channel number) of the target cell (305) may be the same as the EARFCN of the source cell (303). However, the present invention is not limited thereto, and the frequency band supported by the target cell (305) may be different from the frequency band supported by the source cell (303).

[0066] If the target cell (305) accepts the HO request, it can transmit an ack for the HO request to the source cell (303) in operation 315.

[0067] When the source cell (303) receives an ACK for a HO request from the target cell (305), in operation 317, the source cell (303) may transmit a HO command to the electronic device (301) instructing a handover from the source cell (303) to the target cell (305). The HO command may be transmitted to the electronic device (301) via, for example, an RRC Connection Reconfiguration message.

[0068] The HO command may include physical random access channel (PRACH) configuration information. The PRACH configuration information may include information used by the electronic device (301) to generate a RACH (random access channel) preamble and / or information about resources (e.g., time and / or frequency) used by the electronic device (301) to transmit the RACH preamble. For example, the PRACH configuration information may include a first parameter (e.g., root sequence index) used to obtain a predetermined sequence (e.g., root Zadooff-Chu sequence), a second parameter (e.g., PRACH-ConfigIndex) used to determine the format and subframe of the RACH preamble, and a cyclic shift (N) used to generate the RACH preamble. CS ) is in the restricted set or the unrestricted set, a third parameter (e.g. highSpeedFlag), a circular shift (N CS ) may include at least one or all of a fourth parameter (e.g., ZeroCorrelationZoneConfig) used to configure a zero correlation zone, or a fifth parameter (e.g., PRACH frequency offset (PRACH-FreqOffset)) used to determine the location (e.g., location in the frequency domain) of the RACH preamble.

[0069] The electronic device (301) may drive (or start) the T304 timer at operation 319 when receiving a HO command from the source cell (303). If the handover of the electronic device (301) is not successful until the T304 timer expires, the handover of the electronic device (301) may fail. If the handover fails, the electronic device (301) may be connected to the source cell (303).

[0070] After transmitting the HO command, the source cell (303) can transmit the sequence number (SN) status for data (e.g., uplink data and / or downlink data) to the target cell (305) in operation 321.

[0071] In operation 323, the electronic device (301) may attempt random access (RA) to the target cell (305) upon receiving an HO command. The electronic device (301) may generate a RACH preamble based on the PRACH configuration information of the HO command. The electronic device (301) may attempt RA to the target cell (305) by transmitting the generated RACH preamble to the target cell (305).

[0072] In operation 325, the target cell (305) can transmit a random access response (RAR) to the electronic device (301) within a set time.

[0073] If the electronic device (301) receives an RAR from the target cell (305) within a predetermined time, the electronic device (301) can transmit a HO completion message to the target cell (305) in operation 327. If the electronic device (301) receives an RAR from the target cell (305), the electronic device (301) can determine that the HO is successful and can transmit a HO completion message to the target cell (305).

[0074] The electronic device (301) can stop the T304 timer when it transmits the HO completion message.

[0075] The electronic device (301) can receive downlink data from the target cell (305) or transmit uplink data to the target cell (305).

[0076] Unlike the example illustrated in FIG. 3, the electronic device (301) may attempt RA in operation 323 but may not receive RAR from the target cell (305) within a predetermined time and may reattempt RA to the target cell (305). The electronic device (301) may not receive RAR from the target cell (305) despite the RA retry. The electronic device (301) may not receive RAR for each of the RAs attempted multiple times during the handover from the target cell. The electronic device (301) may not receive RAR multiple times during the handover because the PRACH configuration information in the HO command does not match the PRACH configuration information in the SIB2 of the target cell (305). RAR failure (or RAR reception failure) of the electronic device (301) may occur repeatedly. If the T304 timer expires because the electronic device (301) fails to receive a RAR from the target cell for each RA attempted multiple times, the handover of the electronic device (301) may fail. If the handover fails (or such handover failures are repeated), a call drop may occur in the electronic device (301).

[0077] According to one embodiment, as will be described later, if the electronic device (301) fails to receive an RAR multiple times during a handover, the electronic device (301) may attempt an RA to the target cell (305), for example, based on PRACH configuration information in SIB2 of the target cell (305). As another example, if the electronic device (301) fails to receive an RAR multiple times during a handover, the electronic device (301) may check whether the PRACH configuration information used in the initial RA that was previously successful to the target cell (305) is the same as the PRACH configuration information in the HO command, and if the PRACH configuration information used in the initial RA that was previously successful is different from the PRACH configuration information in the HO command, the electronic device may attempt an RA to the target cell (305) based on the PRACH configuration information used in the initial RA.

[0078] FIGS. 4 and 5 are diagrams illustrating an example of an operation of an electronic device storing PRACH configuration information in a first table after a handover failure according to one embodiment.

[0079] Referring to FIG. 4, in operation 411, an electronic device (301) according to an embodiment may receive an HO command including first PRACH configuration information from a source cell (303).

[0080] In operation 413, the electronic device (301) may drive the T304 timer when receiving a HO command from the source cell (303).

[0081] In operation 415, the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information when the T304 timer is driven. The electronic device (301) may generate a first RACH preamble using the first PRACH configuration information. The electronic device (301) may attempt RA to the target cell (305) by transmitting the first RACH preamble to the target cell (305).

[0082] The target cell (305) may not be able to transmit an RAR to the electronic device (301) within a predetermined time. The electronic device (301) may not be able to receive an RAR from the target cell (305) within a predetermined time. In this case, in operation 417, the electronic device (301) may attempt an RA to the target cell (305) based on the first PRACH configuration information.

[0083] The target cell (305) may not be able to transmit the RAR for operation 417 to the electronic device (301) within a predetermined time. The electronic device (301) may not be able to receive the RAR for operation 417 from the target cell (305) within a predetermined time.

[0084] The RA attempt and RAR failure of the electronic device (301) may be repeated.

[0085] In operation 419, the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information.

[0086] The target cell (305) may not be able to transmit the RAR for operation 417 to the electronic device (301) within a predetermined time. The electronic device (301) may not be able to receive the RAR for operation 417 from the target cell (305) within a predetermined time.

[0087] While the T304 timer is running, the electronic device (301) may attempt multiple RA attempts to the target cell (305), but may not receive an RAR for each of the multiple RA attempts from the target cell (305), and the T304 timer may expire. If the T304 timer expires, the handover of the electronic device (301) may fail.

[0088] If the handover of the electronic device (301) fails after multiple occurrences of RAR non-reception, in operation 421, the electronic device (301) may store (or record) the first PRACH configuration information in a first table (e.g., the first table (500) of FIG. 5). The electronic device (301) may store (or record) the first PRACH configuration information that caused multiple occurrences of RAR non-reception and the handover failure in the first table (500).

[0089] For example, in the example illustrated in FIG. 5, the electronic device (301) may store (or record) in the first table (500) an identifier (e.g., a physical cell id (PCI)) (e.g., PCI "86" in FIG. 5) (512) of the target cell (305) and / or a number (e.g., an EARFCN) (e.g., an EARFCN "1694" in FIG. 5) of a frequency band supported by the target cell (305). The electronic device (301) may store (or record) first PRACH configuration information (e.g., root sequence index "740" (513), PRACH-ConfigIndex "5" (514), highSpeedFlag "False" (515), ZeroCorrelationZoneConfig "12" (516), and PRACH-FreqOffset "3" (517) of FIG. 5) mapped to an identifier (512) of a target cell (305) in the first table (500).

[0090] In the example illustrated in FIG. 5, the identifier (512) of the target cell (305) and the number (511) of the frequency band supported by the target cell (305) are located in the same column in the first table (500), but this is merely exemplary, and the identifier (512) of the target cell (305) and the number (511) of the frequency band supported by the target cell (305) may be located in different columns.

[0091] FIGS. 6 and 7 are diagrams illustrating an example of an operation of an electronic device according to one embodiment of the present invention to store PRACH configuration information in a second table after a successful handover.

[0092] Referring to FIG. 6, in operation 611, an electronic device (301) according to an embodiment may receive an HO command including first PRACH configuration information from a source cell (303).

[0093] At operation 613, the electronic device (301) may drive the T304 timer.

[0094] While the T304 timer is running, the electronic device (301) may attempt RA to the target cell (305) multiple times, but may not receive an RAR for each of the RAs attempted multiple times from the target cell (305). For example, in operation 615, the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information. The target cell (305) may not transmit the RAR for operation 615 to the electronic device (301) within a predetermined time. The electronic device (301) may not receive the RAR for operation 615 from the target cell (305) within a predetermined time. In this case, in operation 617, the electronic device (301) may reattempt RA to the target cell (305) based on the first PRACH configuration information. The target cell (305) may not be able to transmit the RAR for operation 617 to the electronic device (301) within a predetermined time. The electronic device (301) may not be able to receive the RAR for operation 617 from the target cell (305) within a predetermined time.

[0095] If the electronic device (301) fails to receive an RAR for each of the RAs attempted multiple times from the target cell (305), in operation 619, the electronic device (301) may attempt an RA to the target cell (305) based on the second PRACH configuration information in the SIB (system information block) 2 of the target cell (305). For example, the electronic device (301) may determine whether the first PRACH configuration information and the second PRACH configuration information are the same. If the first PRACH configuration information and the second PRACH configuration information are different from each other, the electronic device (301) may generate a second RACH preamble using the second PRACH configuration information, and transmit the second RACH preamble to the target cell (305).

[0096] In operation 621, the target cell (305) may transmit an RAR (e.g., an RAR for RA based on the second PRACH configuration information) to the electronic device (301).

[0097] When the electronic device (301) receives an RAR from the target cell (305), the electronic device (301) may transmit a HO complete message to the target cell (305) at operation 623. At operation 625, the electronic device (301) may stop the T304 timer. The HO of the electronic device (301) may be successful.

[0098] In operation 627, the electronic device (301) may store (or record) second PRACH configuration information in a second table (e.g., second table (700) of FIG. 7). If the first PRACH configuration information that caused multiple occurrences of RAR non-reception is different from the second PRACH configuration information that resulted in HO success, the electronic device (301) may store (or record) the second PRACH configuration information in the second table (700).

[0099] For example, in the example illustrated in FIG. 7, the electronic device (301) may store (or record) an identifier of the target cell (305) (e.g., PCI "86" (712) of FIG. 7) and / or a number of a frequency band supported by the target cell (305) (e.g., EARFCN "1694" (711) of FIG. 7) in the second table (700). The electronic device (301) may store (or record) second PRACH configuration information (e.g., root sequence index "250" (713), PRACH-ConfigIndex "5" (714), highSpeedFlag "False" (715), ZeroCorrelationZoneConfig "12" (716), and PRACH-FreqOffset "3" (717) of FIG. 7) in the second table (700) to be mapped to the identifier (712) of the target cell (305). In the example illustrated in FIG. 7, the root sequence index "250" (713) of the second PRACH configuration information may be different from the root sequence index "740" (513) of the first PRACH configuration information of FIG. 5. Since the root sequence index "740" (513) of the first PRACH configuration information is different from the root sequence index "250" (713) of the second PRACH configuration information, RAR non-reception may occur multiple times.

[0100] In the example illustrated in FIG. 7, the identifier (712) of the target cell (305) and the number (711) of the frequency band supported by the target cell (305) are located in the same column in the second table (700), but this is merely exemplary, and the identifier (712) of the target cell (305) and the number (711) of the frequency band supported by the target cell (305) may be located in different columns.

[0101] FIG. 8 is a flowchart illustrating an example of the operation of an electronic device according to one embodiment.

[0102] Referring to FIG. 8, an electronic device (301) according to an embodiment may receive an HO command including first PRACH configuration information from a source cell (303) in operation 811. When the electronic device (301) receives the HO command from the source cell (303), the electronic device (301) may drive a T304 timer.

[0103] In operation 813, the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information.

[0104] In operation 815, the electronic device (301) may determine (or check) whether the RA (e.g., the RA based on the first PRACH configuration information) is successful. For example, the electronic device (301) may determine (or check) that the RA is successful if it receives an RAR from the target cell (305). The electronic device (301) may determine (or check) that the RA is not successful (or that the RA has failed) if it does not receive an RAR from the target cell (305).

[0105] If the electronic device (301) determines that the RA is successful (e.g., receives an RAR from the target cell (305)) (operation 815-Yes), it may transmit an HO complete message to the target cell (305) in operation 817.

[0106] If the electronic device (301) determines that the RA is not successful (operation 815-No), then in operation 819, the electronic device (301) may determine whether the signal quality (e.g., at least one of signal to interference plus noise ratio (SINR), reference signal received power (RSRP), or reference signal received quality (RSRQ)) of the target cell (305) is above a predetermined level. For example, the electronic device (301) may determine whether the SINR of the target cell (305) is above a threshold value (e.g., 10 dB).

[0107] If the electronic device (301) determines that the signal quality of the target cell (305) is above a predetermined level (e.g., if the SINR of the target cell (305) is determined to be above a threshold value) (operation 819-Yes), in operation 821, it can check whether the RAR of the target cell (305) has not been received n or more times (or whether the RAR has not been received multiple times). Here, n can represent an integer greater than or equal to 2.

[0108] If the electronic device (301) determines that the RAR of the target cell (305) has not been received n or more times (operation 821 - Yes), the electronic device (301) may check whether the SIB2 of the target cell (305) is received in operation 823. If the SIB2 of the target cell (305) is broadcast while the T304 timer is running, the electronic device (301) may receive the SIB2 from the target cell (305). If the SIB2 of the target cell (305) is not broadcast while the T304 timer is running, the electronic device (301) may not be able to receive the SIB2 from the target cell (305).

[0109] When the electronic device (301) receives SIB2 of the target cell (305) (operation 823-Yes), in operation 825, the electronic device (301) can obtain second PRACH configuration information from SIB2 of the target cell (305).

[0110] In operation 827, the electronic device (301) may determine whether the first PRACH configuration information and the second configuration information are the same. The electronic device (301) may determine whether the PRACH configuration information (e.g., the first PRACH configuration information) in the HO command and the PRACH configuration information (e.g., the second PRACH configuration information) in the SIB2 are the same.

[0111] If the electronic device (301) determines that the first PRACH configuration information and the second PRACH configuration information are not the same (operation 827-No), in operation 829, the electronic device (301) may attempt RA to the target cell (305) based on the second PRACH configuration information. The electronic device (301) may transmit a second RACH preamble generated using the second PRACH configuration information to the target cell (305).

[0112] If the electronic device (301) attempts RA to the target cell (305) based on the second PRACH configuration information, the electronic device (301) can check whether the HO is successful in operation 831. For example, the electronic device (301) can receive an RAR for the second RACH preamble from the target cell (305), and if the RAR for the second RACH preamble is received, the electronic device (301) can transmit an HO completion message to the target cell (305). The electronic device (301) can check that the HO is successful by transmitting the HO completion message to the target cell (305). If the T304 timer expires without receiving an RAR for the second RACH preamble, the electronic device (301) can check that the HO is unsuccessful.

[0113] If the HO is successful (operation 831 - Yes), the electronic device (301) may store (or record) the second PRACH configuration information in a second table (e.g., the second table (700) of FIG. 7) in operation 833.

[0114] The electronic device (301) can connect to the source cell (303) in operation 835 if the HO is unsuccessful (operation 831-No).

[0115] If the signal quality of the target cell (305) is not higher than a predetermined level (operation 819-No), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 839.

[0116] If the electronic device (301) has not received the RAR of the target cell (305) n times (e.g., if the RAR has not been received once) (operation 821-No), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 839.

[0117] If the first PRACH configuration information and the second PRACH configuration information are the same (operation 827 - Yes), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 839.

[0118] If the electronic device (301) does not receive the SIB2 of the target cell (305) (operation 823-No), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 837.

[0119] According to one embodiment, the electronic device (301) may receive an additional HO command from the source cell (303) that instructs HO from the source cell (303) to the target cell (305). If HO according to the additional HO command is successful, the electronic device (301) may delete (or remove) the second PRACH configuration information from the second table.

[0120] FIGS. 9, 10, and 11 are flowcharts illustrating examples of the operation of an electronic device according to one embodiment.

[0121] Referring to FIG. 9, a second table (900) (e.g., the second table (700) of FIG. 7) storing cell identifiers (e.g., PCI) and PRACH configuration information is illustrated. In the example illustrated in FIG. 9, identifier #1 (e.g., PCI of cell #1) in the second table (900) may be mapped to PRACH configuration information #1, and identifier #2 (e.g., PCI of cell #2) may be mapped to PRACH configuration information #2.

[0122] According to one embodiment, when storing PRACH configuration information #1 in the second table (900), the electronic device (301) may set the validity period of the PRACH configuration information #1 to a timer value and may operate a timer (hereinafter referred to as “first timer”) having the set timer value. The validity period of the PRACH configuration information #1 may be, for example, one week or one month, but is not limited thereto. When the first timer expires, the electronic device (301) may delete (or remove) the identifier #1 and the PRACH configuration information #1 from the second table (900).

[0123] According to one embodiment, when storing PRACH configuration information #2 in the second table (900), the electronic device (301) may set the validity period of the PRACH configuration information #2 as a timer value and may operate a timer (hereinafter referred to as a “second timer”) having the set timer value. The validity period of the PRACH configuration information #2 may be, for example, one week or one month, but is not limited thereto. When the second timer expires, the electronic device (301) may delete (or remove) the identifier #2 and the PRACH configuration information #2 from the second table (900).

[0124] Referring to FIG. 10, an electronic device (301) according to an embodiment may receive an HO command including first PRACH configuration information from a source cell (303) in operation 1011. When the electronic device (301) receives the HO command, the electronic device (301) may drive a T304 timer.

[0125] According to one embodiment, each of the first timer and the second timer described through FIG. 9 may be in a running state.

[0126] When the electronic device (301) receives the HO command, it can check whether the identifier of the target cell (305) is present in the second table (900) in operation 1013. For example, the identifier of the target cell (305) may be identifier #1. Since the second table (900) may have identifier #1, the electronic device (301) can check whether the identifier of the target cell (305) is present in the second table (900).

[0127] If the electronic device (301) checks that there is no identifier of the target cell (305) in the second table (900) (operation 1013-No), the electronic device (301) can perform operation 1111 of FIG. 11.

[0128] If the electronic device (301) checks that the identifier of the target cell (305) exists in the second table (900) (operation 1013 - Yes), in operation 1015, the electronic device (301) may obtain PRACH configuration information (e.g., PRACH configuration information #1 of FIG. 9) mapped to the identifier (e.g., identifier #1) of the target cell (305) in the second table (900). In operation 1017, the electronic device (301) may attempt RA to the target cell (305) based on the obtained PRACH configuration information (e.g., PRACH configuration information #1 of FIG. 9). If the electronic device (301) checks that the identifier of the target cell (305) is present in the second table (900) (operation 1013-Yes), the electronic device (301) may attempt RA to the target cell (305) by first using the PRACH configuration information mapped to the identifier of the target cell (305) rather than the first PRACH configuration information.

[0129] According to an embodiment, if the electronic device (301) checks that the identifier of the target cell (305) is present in the second table (900) (operation 1013 - Yes), the electronic device (301) may attempt an RA to the target cell (305) using the first PRACH configuration information before the PRACH configuration information mapped to the identifier of the target cell (305). The electronic device (301) may attempt an RA based on the first PRACH configuration information multiple times, but may not receive an RAR for each of the multiple attempted RAs from the target cell (305). In this case, the electronic device (301) may obtain the PRACH configuration information mapped to the identifier of the target cell (305) from the second table (900), and attempt an RA to the target cell (305) based on the obtained PRACH configuration information.

[0130] According to an embodiment, if the electronic device (301) checks that the identifier of the target cell (305) is present in the second table (900) (operation 1013-Yes), the electronic device (301) may acquire PRACH configuration information mapped to the identifier of the target cell (305) in the second table (900), and may alternately attempt an RA based on the first PRACH configuration information and an RA based on the acquired PRACH configuration information. For example, if the electronic device (301) checks that the identifier of the target cell (305) is present in the second table (900), the electronic device (301) may attempt an RA based on the first PRACH configuration information, and if the electronic device (301) does not receive an RAR for the RA based on the first PRACH configuration information from the target cell (305), the electronic device (301) may attempt an RA based on the acquired PRACH configuration information.

[0131] In operation 1019, the electronic device (301) can check whether the HO is successful. For example, if the electronic device (301) receives an RAR (e.g., an RAR for an RA based on PRACH configuration information #1 of FIG. 9) from the target cell (305), the electronic device (301) can transmit a HO complete message to the target cell (305). The electronic device (301) can check that the HO is successful by transmitting the HO complete message. If the T304 timer expires without receiving an RAR from the target cell (305), the electronic device (301) can check that the HO is unsuccessful.

[0132] If the HO is successful (operation 1019 - Yes), in operation 1021, the electronic device (301) may reset a timer (e.g., a first timer) for PRACH configuration information (e.g., PRACH configuration information #1) mapped to the identifier of the target cell (305). For example, if the HO is successful (operation 1019 - Yes), a time (e.g., 500) may elapse from the timer value of the first timer (e.g., the validity period "1000" of PRACH configuration information #1) and the remaining time may be 500. If the HO is successful, the electronic device (301) may reset the validity period (e.g., 1000) of PRACH configuration information #1 to the timer value of the first timer. The electronic device (301) may drive the reset first timer.

[0133] If the HO is not successful (or the HO fails) (operation 1019-No), the electronic device (301) may, in operation 1023, delete (or remove) the PRACH configuration information (e.g., PRACH configuration information #1) mapped to the identifier of the target cell (305) from the second table (900).

[0134] If there is no identifier of the target cell (305) in the second table (900) (operation 1013-No), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 1111 of FIG. 11.

[0135] In operation 1113, the electronic device (301) may determine (or check) whether the RA (e.g., the RA based on the first PRACH configuration information) is successful. For example, the electronic device (301) may determine (or check) that the RA is successful if it receives an RAR from the target cell (305). If the electronic device (301) does not receive an RAR from the target cell (305), it may determine (or check) that the RA is not successful (or that the RA has failed).

[0136] If the electronic device (301) determines that the RA is successful (e.g., receives an RAR from the target cell (305)) (operation 1113-Yes), it may transmit an HO complete message to the target cell (305) in operation 1115.

[0137] If the electronic device (301) determines that the RA is not successful (operation 1113-No), the electronic device (301) may determine whether the signal quality of the target cell (305) is above a predetermined level in operation 1117. For example, the electronic device (301) may determine whether the SINR of the target cell (305) is above a threshold value (e.g., 10 dB).

[0138] If the electronic device (301) determines that the signal quality of the target cell (305) is above a predetermined level (operation 1117 - Yes), in operation 1119, it can check whether the RAR of the target cell (305) has not been received n or more times (or whether the RAR has not been received multiple times). Here, n can represent an integer greater than or equal to 2.

[0139] If the electronic device (301) checks that the RAR of the target cell (305) has not been received n or more times (operation 1119 - Yes), it can check whether the SIB2 of the target cell (305) is received in operation 1121.

[0140] When the electronic device (301) receives SIB2 of the target cell (305) (operation 1121-Yes), in operation 1123, the electronic device (301) can obtain second PRACH configuration information from SIB2 of the target cell (305).

[0141] In operation 1125, the electronic device (301) may determine whether the first PRACH configuration information and the second configuration information are the same.

[0142] If the electronic device (301) determines that the first PRACH configuration information and the second PRACH configuration information are not the same (operation 1125-No), in operation 1127, the electronic device may attempt RA to the target cell (305) based on the second PRACH configuration information.

[0143] When the electronic device (301) attempts RA to the target cell (305) based on the second PRACH configuration information, it can check whether the HO is successful in operation 1129.

[0144] If the HO is successful (operation 1129 - Yes), the electronic device (301) may store (or record) the second PRACH configuration information in a second table (e.g., the second table (700) of FIG. 7 or the second table (900) of FIG. 9) in operation 1131.

[0145] If the HO is not successful (operation 1129-No), the electronic device (301) may store (or record) the first PRACH configuration information in the first table (e.g., the first table (500) of FIG. 5) in operation 1133.

[0146] If the signal quality of the target cell (305) is not higher than a predetermined level (operation 1117-No), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 1137.

[0147] If the electronic device (301) has not received the RAR of the target cell (305) n times (e.g., if the RAR has not been received once) (operation 1119-No), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 1137.

[0148] If the first PRACH configuration information and the second PRACH configuration information are the same (operation 1125 - Yes), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 1137.

[0149] If the electronic device (301) does not receive the SIB2 of the target cell (305) (Operation 1121 - No), the electronic device (301) may check whether the T304 timer has expired in operation 1135, and if the T304 timer has not expired (Operation 1135 - No), the electronic device (301) may attempt RA to the target cell (305) based on the first PRACH configuration information in operation 1137. If the T304 timer has expired (Operation 1135 - Yes), the electronic device (301) may perform operation 1133.

[0150] The electronic device (301) can check whether the HO was successful in operation 1139 when operation 1137 was performed.

[0151] The electronic device (301) may perform operation 1133 if the HO is not successful (operation 1137-No).

[0152] The operation of the electronic device (101) described through FIG. 1, the electronic device (201) described through FIG. 2, and the operation of the electronic device (301) described through FIGS. 3 to 8 can be applied to the electronic device (301) of FIGS. 9 to 11.

[0153] FIGS. 12, 13, and 14 are flowcharts illustrating examples of the operation of an electronic device according to one embodiment.

[0154] Referring to FIG. 12, an electronic device (301) according to an embodiment may check whether an initial RA for a cell (e.g., a second cell (1303) of FIG. 13) has a history of success in operation 1211. The electronic device (301) may check whether an initial RA for a cell (e.g., a second cell (1303) of FIG. 13) has ever been successful. The initial RA may, for example, represent an RA performed when the electronic device (301) accesses a target cell (305) in idle mode.

[0155] For example, in the example illustrated in FIG. 13, the electronic device (301) may be located in the area of ​​the first cell (1301) and the area of ​​the second cell (1303). The electronic device (301) of FIG. 13 may be in an idle mode. The electronic device (301) may select the second cell (1303) among the first cell (1301) and the second cell (1303) in the idle mode. The electronic device (301) may attempt an RA to the second cell (1303) based on the PRACH configuration information in the SIB2 of the second cell (1303) and may receive an RAR from the second cell (1303). When the electronic device (301) receives an RAR from the second cell (1303), it may determine that the initial RA for the second cell (1303) is successful, and may store information indicating that the initial RA for the second cell (1303) is successful in a memory (e.g., the memory (130) of FIG. 1).

[0156] Returning to FIG. 12, if the electronic device (301) has a history of successful initial RA for a cell (e.g., the second cell (1303)) (or checks that the initial RA for the cell has been successful) (operation 1211-Yes), then in operation 1213, the electronic device may check whether the identifier (e.g., PCI) of the cell (e.g., the second cell (1303)) is in the first table (1400) (e.g., the first table (500) of FIG. 5).

[0157] The electronic device (301) may perform operation 1221 if the identifier of the cell (e.g., the second cell (1303)) is not in the first table (1400) (operation 1213-No).

[0158] If the identifier of the cell (e.g., the second cell (1303)) is in the first table (1400) (operation 1213-Yes), the electronic device (301) may obtain PRACH configuration information mapped to the identifier of the cell (e.g., the second cell (1303)) from the first table (1400) in operation 1215. For example, the identifier of the second cell (1303) may be an identifier B It can be. The identifier of the second cell (1303) in the first table (1400) (e.g. identifier B ) may be present, the electronic device (301) may have an identifier in the first table (1400). B PRACH configuration information mapped to B can be obtained.

[0159] In operation 1217, the electronic device (301) obtains PRACH configuration information (e.g., PRACH configuration information of FIG. 14) from the first table (1400) used for the initial RA. B) can be determined to be the same as the PRACH configuration information used in the initial RA. The PRACH configuration information used in the initial RA may correspond to, for example, the PRACH configuration information in SIB2 received by the electronic device (301) from the second cell (1303) in idle mode.

[0160] If the PRACH configuration information used in the initial RA is the same as the PRACH configuration information obtained from the first table (1400) (operation 1217 - Yes), the electronic device (301) may delete (or remove) the PRACH configuration information mapped to the identifier of the cell (e.g., the second cell (1303)) from the first table (1400) in operation 1219. The first table (1400) may be a table for recording the PRACH configuration information that caused multiple occurrences of RAR non-reception and handover failure. The PRACH configuration information obtained from the first table (1400) (e.g., the PRACH configuration information of FIG. 14) B ) is the same as the PRACH configuration information used in the successful initial RA, so the PRACH configuration information obtained from the first table (1400) (e.g., the PRACH configuration information of FIG. 14) B ) may not cause multiple occurrences of RAR non-reception and handover failure. The electronic device (301) may use the PRACH configuration information used in the initial RA and the PRACH configuration information obtained from the first table (1400) (e.g., the PRACH configuration information of FIG. 14). B ) are the same, the acquired PRACH configuration information (e.g., the PRACH configuration information of FIG. 14) B ) can be deleted from the first table (1400).

[0161] If the PRACH configuration information used in the initial RA is not the same as the PRACH configuration information obtained from the first table (1400) (operation 1217-No), the electronic device (301) may store (or record) the PRACH configuration information used in the initial RA in a second table (e.g., the second table (700) of FIG. 7 or the second table (900) of FIG. 9) in operation 1221. Together with the PRACH configuration information used in the initial RA, the electronic device (301) may store an identifier of a cell that succeeded in the initial RA (e.g., the second cell (1303)) in the second table (700, 900). In the second table (700, 900), the identifier of the cell that succeeded in the initial RA (e.g., the second cell (1303)) and the PRACH configuration information used in the initial RA may be mapped.

[0162] If the electronic device (301) stores (or records) the PRACH configuration information used in the initial RA in the second table (700, 900), in operation 1223, the electronic device (301) may drive a timer for the PRACH configuration information used in the initial RA. For example, the electronic device (301) may set the validity period of the PRACH configuration information used in the initial RA to a timer value, and may drive a timer having the set timer value.

[0163] According to one embodiment, an electronic device (301) may be connected to a first cell (1301) of FIG. 13. The electronic device (301) may receive a HO command from the first cell (1301) that instructs HO to a second cell (1303) while connected to the first cell (1301). In this case, the first cell (1301) may be a source cell (303) and the second cell (1303) may be a target cell (305). The electronic device (301) may attempt RA to the second cell (1303) multiple times based on PRACH configuration information in the HO command of the first cell (1301), but may not receive an RAR for each of the multiple RAs from the second cell (1303). The electronic device (301) may not receive an RAR multiple times. In this case, the electronic device (301) can check whether there is an identifier of the second cell (1303) in the second table (700, 900). If there is an identifier of the second cell (1303) in the second table (700, 900), the electronic device (301) can obtain PRACH configuration information (e.g., PRACH configuration information used for initial RA) mapped to the identifier of the second cell (1303) from the second table (700, 900). The electronic device (301) can attempt RA to the second cell (1303) based on the PRACH configuration information (e.g., PRACH configuration information used for initial RA) obtained from the second table (700, 900). Accordingly, HO failure of the electronic device (301) may not occur.

[0164] FIGS. 15 and 16 are drawings illustrating examples of the operation of an electronic device according to one embodiment.

[0165] Referring to FIG. 15, an electronic device (301) according to an embodiment can check whether there is a history of a successful first HO from a first cell (1601) to a third cell (1605) and a successful second HO from the third cell (1605) to a second cell (1603) in operation 1511. The electronic device (301) can check whether there is a history of a successful first HO and a successful second HO.

[0166] For example, in the example illustrated in FIG. 16, the electronic device (301) may be connected to a first cell (1601), and a second cell (1603) and a third cell (1605) may be adjacent cells of the first cell (1601). The frequency band of the first cell (1601) may be different from the frequency band of the third cell (1605), and the frequency band of the second cell (1603) may be the same as the frequency band of the third cell (1605). When the first HO from the first cell (1601) to the third cell (1605) and the second HO from the third cell (1605) to the second cell (1603) are successful, the electronic device (301) may store information indicating that the first HO and the second HO were successful in a memory (e.g., the memory (130) of FIG. 1).

[0167] If the electronic device (301) has a history of success between the first HO and the second HO (or checks that the first HO and the second HO have succeeded) (operation 1511-Yes), in operation 1513, the electronic device (301) can check whether the identifier of the second cell (1603) is in the first table (1400) (e.g., the first table (500) of FIG. 5).

[0168] The electronic device (301) may perform operation 1521 if the identifier of the second cell (1603) is not in the first table (1400) (operation 1513-No).

[0169] If the identifier of the second cell (1603) is in the first table (1400) (operation 1513-Yes), the electronic device (301) may obtain PRACH configuration information mapped to the identifier of the second cell (1603) from the first table (1400) in operation 1515. For example, the identifier of the second cell (1603) may be an identifier B It can be. The identifier of the second cell (1603) in the first table (1400) (e.g. identifier B ) may be present, the electronic device (301) may have an identifier in the first table (1400). B PRACH configuration information mapped to B can be obtained.

[0170] In operation 1517, the electronic device (301) receives the PRACH configuration information in the HO command indicating the second HO from the first table (1400) (e.g., the PRACH configuration information of FIG. 14). B ) can be determined to be identical.

[0171] If the PRACH configuration information in the HO command indicating the second HO is the same as the PRACH configuration information obtained from the first table (1400) (operation 1217 - Yes), the electronic device (301) may delete (or remove) the PRACH configuration information mapped to the identifier of the second cell (1603) from the first table (1400) in operation 1519.

[0172] If the PRACH configuration information in the HO command indicating the second HO is not the same as the PRACH configuration information obtained from the first table (1400) (operation 1517-No), the electronic device (301) may store (or record) the PRACH configuration information in the HO command indicating the second HO in a second table (e.g., the second table (700) of FIG. 7 or the second table (900) of FIG. 9) in operation 1521. Together with the PRACH configuration information in the HO command indicating the second HO, the electronic device (301) may store the identifier of the second cell (1603) in the second table (700, 900). On the second table (700, 900), the identifier of the second cell (1603) and the PRACH configuration information in the HO command indicating the second HO may be mapped.

[0173] If the electronic device (301) stores (or records) the PRACH configuration information within the HO command indicating the second HO in the second table (700, 900), in operation 1523, the electronic device (301) may drive a timer for the PRACH configuration information within the HO command indicating the second HO. For example, the electronic device (301) may set the validity period of the PRACH configuration information within the HO command indicating the second HO to a timer value, and may drive a timer having the set timer value.

[0174] According to one embodiment, the electronic device (301) may receive an HO command from the first cell (1601) indicating HO from the first cell (1601) to the second cell (1603) after being connected to the first cell (1601) of FIG. 16. In this case, the first cell (1601) may be a source cell (303) and the second cell (1603) may be a target cell (305). The electronic device (301) may attempt RA to the second cell (1603) multiple times based on PRACH configuration information in the HO command of the first cell (1601), but may not receive an RAR for each of the multiple RAs from the second cell (1603). The electronic device (301) may not receive an RAR multiple times. In this case, the electronic device (301) can check whether there is an identifier of the second cell (1603) in the second table (700, 900). If there is an identifier of the second cell (1603) in the second table (700, 900), the electronic device (301) can obtain PRACH configuration information (e.g., PRACH configuration information in the HO command indicating the second HO of FIG. 15) mapped to the identifier of the second cell (1603) from the second table (700, 900). The electronic device (301) can attempt RA to the second cell (1603) based on the PRACH configuration information obtained from the second table (700, 900). Accordingly, HO failure of the electronic device (301) may not occur.

[0175] FIG. 17 is a block diagram illustrating an example of a configuration of an electronic device according to one embodiment.

[0176] Referring to FIG. 17, an electronic device (1701) according to one embodiment (e.g., the electronic device (101) of FIG. 1, the electronic device (201) of FIG. 2, and the electronic device (301) of FIGS. 3 to 16) may include a memory (1710) and at least one processor (1720).

[0177] The processor (1720) may include processing circuitry.

[0178] The memory (1710) can store one or more instructions executable by the processor (1720). The instructions stored in the memory (1710) can cause the electronic device (1701) to perform operations of the electronic device (1701) when individually or collectively executed by the processor (1720).

[0179] According to one embodiment, the memory (1710) may store a first table (e.g., the first table (500) of FIG. 5, the first table (1400) of FIG. 14) and / or a second table (e.g., the second table (700) of FIG. 7, the second table (900) of FIG. 9). According to an embodiment, the first table and the second table may be stored in a memory separate from the memory (1710).

[0180] According to one embodiment, an electronic device (1701) (e.g., a processor (1720)) may receive an HO command including first PRACH configuration information from a source cell (e.g., a source cell (303) of FIG. 3).

[0181] According to one embodiment, the electronic device (1701) (e.g., processor (1720)) may attempt the first RA multiple times to a target cell (e.g., target cell (305) of FIG. 3) based on the first PRACH configuration information.

[0182] According to one embodiment, if the electronic device (1701) (e.g., processor (1720)) fails to receive an RAR for each attempted first RA from the target cell, the electronic device (1701) may compare the second PRACH configuration information in a system information message (e.g., SIB2) of the target cell with the first PRACH configuration information.

[0183] According to one embodiment, the electronic device (1701) (e.g., the processor (1720)) may attempt a second RA to the target cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information. The electronic device (1701) (e.g., the processor (1720)) may attempt a first RA until the T304 timer expires when the second PRACH configuration information is the same as the first PRACH configuration information.

[0184] According to one embodiment, the electronic device (1701) (e.g., processor (1720)) may record the first PRACH configuration information in the first table if the HO fails to receive the RAR for each attempted first RA from the target cell.

[0185] According to one embodiment, the electronic device (1701) (e.g., processor (1720)) may record the second PRACH configuration information in the second table if the HO of the electronic device (1701) from the source cell to the target cell is successful after attempting the second RA.

[0186] According to one embodiment, when the electronic device (1701) (e.g., the processor (1720)) receives an HO command from a source cell, the electronic device (1701) (e.g., the processor (1720)) may determine whether the second table contains an identifier of the target cell. When the electronic device (1701) (e.g., the processor (1720)) determines that the second table does not contain an identifier of the target cell (e.g., operation 1013-No of FIG. 10), the electronic device may attempt the first RA multiple times, and when the RAR for each attempted first RA is not received, the electronic device may compare the first PRACH configuration information with the second first PRACH configuration information, and when the first PRACH configuration information and the second first PRACH configuration information are different, the electronic device may attempt the second RA.

[0187] According to one embodiment, when the electronic device (1701) (e.g., the processor (1720)) determines that the identifier of the target cell is in the second table (e.g., operation 1013-example of FIG. 10), the electronic device (1701) (e.g., the processor (1720)) may acquire PRACH configuration information (e.g., PRACH configuration information #1 of FIG. 9) mapped to the identifier of the target cell in the second table. The electronic device (1701) (e.g., the processor (1720)) may attempt RA to the target cell based on the acquired PRACH configuration information.

[0188] According to one embodiment, the electronic device (1701) (e.g., the processor (1720)) may check whether there is a first history of successful initial RA for a second cell (e.g., the second cell (1303) of FIG. 13). If the electronic device (1701) (e.g., the processor (1720)) determines that there is a first history, the electronic device (1701) (e.g., the processor (1720)) may determine whether the identifier of the second cell is in the first table. If the electronic device (1701) (e.g., the processor (1720)) determines that the identifier of the second cell is in the first table, the electronic device (1701) (e.g., the processor (1720)) may obtain PRACH configuration information mapped to the identifier of the second cell from the first table. The electronic device (1701) (e.g., the processor (1720)) may determine whether the PRACH configuration information used for the initial RA and the PRACH configuration information obtained from the first table are the same. If the electronic device (1701) (e.g., processor (1720)) determines that the PRACH configuration information used in the initial RA and the acquired PRACH configuration information are different, the electronic device (1701) (e.g., processor (1720)) may record the PRACH configuration information used in the initial RA in a second table. If the electronic device (1701) (e.g., processor (1720)) determines that the PRACH configuration information used in the initial RA and the acquired PRACH configuration information are the same, the electronic device (1701) may delete the PRACH configuration information mapped to the identifier of the second cell from the first table.

[0189] According to one embodiment, the electronic device (1701) (e.g., the processor (1720)) can check whether there is a second history in which a first HO of the electronic device (1701) succeeds from a first cell (e.g., the first cell (1601) of FIG. 16) to a third cell (e.g., the third cell (1605) of FIG. 16)) and a second HO of the electronic device (1701) succeeds from the third cell to a second cell (e.g., the second cell (1603) of FIG. 16). If the electronic device (1701) (e.g., the processor (1720)) checks that there is a second history, it can determine whether the identifier of the second cell is recorded in the first table. If the electronic device (1701) (e.g., processor (1720)) determines that the identifier of the second cell is recorded in the first table, the electronic device (1701) (e.g., processor (1720)) can obtain PRACH configuration information mapped to the identifier of the second cell from the first table. The electronic device (1701) (e.g., processor (1720)) can determine whether the PRACH configuration information in the HO command indicating the second HO and the obtained PRACH configuration information are the same. If the electronic device (1701) (e.g., processor (1720)) determines that the PRACH configuration information in the HO command indicating the second HO and the obtained PRACH configuration information are different, the electronic device (1701) (e.g., processor (1720)) can record the PRACH configuration information in the HO command indicating the second HO in the second table. If the electronic device (1701) (e.g., processor (1720)) determines that the PRACH configuration information in the HO command that instructed the second HO is the same as the acquired PRACH configuration information, the electronic device (1701) may delete the PRACH configuration information mapped to the identifier of the second cell in the first table.

[0190] The embodiments described through FIGS. 1 to 15 can be applied to the electronic device (1701) of FIG. 16.

[0191] FIG. 18 is a flowchart illustrating an example of a method of operating an electronic device according to one embodiment.

[0192] Referring to FIG. 18, in operation 1810, an electronic device (101, 201, 301, 1701) may receive a handover command including first PRACH configuration information from a first cell (e.g., a source cell) (e.g., the source cell (303) of FIG. 3, the first cell (1301) of FIG. 13, the first cell (1601) of FIG. 16).

[0193] In operation 1820, the electronic device (101, 201, 301, 1701) may attempt a first random access multiple times to a second cell (e.g., a target cell) (e.g., a target cell (305) of FIG. 3, a second cell (1303) of FIG. 13, a second cell (1603) of FIG. 16) based on the first PRACH configuration information.

[0194] At operation 1830, if the electronic device (101, 201, 301, 1701) does not receive an RAR for each attempted first random access from the second cell, the electronic device may compare the second PRACH configuration information in the system information message (e.g., SIB2) of the second cell with the first PRACH configuration information.

[0195] In operation 1840, the electronic device (101, 201, 301, 1701) may attempt a second random access to the second cell based on the second PRACH configuration information if the second PRACH configuration information is different from the first PRACH configuration information.

[0196] According to one embodiment, when the electronic device (101, 201, 301, 1701) receives a handover command including first PRACH configuration information from a first cell, the electronic device (101, 201, 301, 1701) may determine whether an identifier of a second cell is included in a table (e.g., a second table) in which information used for random access of a successful handover (and / or information used for a successful initial random access) of the electronic device (101, 201, 301, 1701) is recorded. When the electronic device (101, 201, 301, 1701) determines that the identifier of the second cell is not included in the table (e.g., the second table), the electronic device (101, 201, 301, 1701) may perform operations 1710 to 1740.

[0197] According to one embodiment, the electronic device (101, 201, 301, 1701) may check whether there is a first history of successful initial random access to a second cell. If the electronic device (101, 201, 301, 1701) determines that there is a first history, the electronic device (101, 201, 301, 1701) may determine whether there is an identifier of the second cell in a table (e.g., a first table) in which information (e.g., PRACH configuration information) used for random access of a failed handover (e.g., a handover in which a T304 timer expires after multiple occurrences of non-reception of RAR) of the electronic device (101, 201, 301, 1701) is recorded. If the electronic device (101, 201, 301, 1701) determines that the identifier of the second cell is recorded in the first table, the electronic device (101, 201, 301, 1701) may obtain PRACH configuration information mapped to the identifier of the second cell from the first table. The electronic device (101, 201, 301, 1701) can determine whether the PRACH configuration information used for initial random access is the same as the PRACH configuration information obtained from the first table.

[0198] According to one embodiment, if the electronic device (101, 201, 301, 1701) determines that the PRACH configuration information used in the initial RA is different from the PRACH configuration information obtained from the first table, the electronic device may record the PRACH configuration information used in the initial RA in the second table. If the electronic device (101, 201, 301, 1701) determines that the PRACH configuration information used in the initial RA is the same as the PRACH configuration information obtained from the first table, the electronic device may delete the PRACH configuration information mapped to the identifier of the second cell in the first table.

[0199] According to one embodiment, the electronic device (101, 201, 301, 1701) can check whether there is a second history in which the first HO of the electronic device (101, 201, 301, 1701) from the first cell to the third cell is successful and the second HO of the electronic device from the third cell to the second cell is successful. If the electronic device (101, 201, 301, 1701) checks that there is a second history, it can determine whether there is an identifier of the second cell in another table (e.g., the first table). If the electronic device (101, 201, 301, 1701) determines that the identifier of the second cell is recorded in the first table, it can obtain PRACH configuration information mapped to the identifier of the second cell from the first table. The electronic device (101, 201, 301, 1701) can determine whether the PRACH configuration information in the HO command indicating the second HO is the same as the PRACH configuration information obtained from the first table.

[0200] According to one embodiment, if the electronic device (101, 201, 301, 1701) determines that the PRACH configuration information in the HO command indicating the second HO is different from the PRACH configuration information acquired from the first table, the electronic device may record the PRACH configuration information in the HO command indicating the second HO in the second table. If the electronic device (101, 201, 301, 1701) determines that the PRACH configuration information in the HO command indicating the second HO is the same as the acquired PRACH configuration information, the electronic device may delete the PRACH configuration information mapped to the identifier of the second cell in the first table.

[0201] The embodiments described through FIGS. 1 to 16 can be applied to the operating method of the electronic device of FIG. 17.

[0202] According to one embodiment, an electronic device (101, 201, 301, 1701) may include a memory (130, 1710) for storing instructions and at least one processor (120, 210, 1720) including a processing circuit. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform an operation of receiving a handover command from a first cell to a second cell, the handover command including first PRACH configuration information. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform an operation of attempting a first random access to the second cell multiple times based on the first PRACH configuration information. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to compare the second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information if the electronic device fails to receive an RAR for each of the attempted first random accesses from the second cell. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to attempt a second random access to the second cell based on the second PRACH configuration information if the second PRACH configuration information is different from the first PRACH configuration information.

[0203] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: record the first PRACH configuration information in a first table if acquiring the second PRACH configuration information fails and handover of the electronic device fails.

[0204] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: record the second PRACH configuration information in a second table if the handover of the electronic device from the first cell to the second cell is successful after attempting the second random access.

[0205] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: record the second PRACH configuration information in a second table, then receive an additional handover command from the first cell that instructs handover from the first cell to the second cell, and if the handover according to the additional handover command is successful, delete the second PRACH configuration information from the second table.

[0206] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: when the handover command is received from the first cell, determine whether an identifier of the second cell is present in a second table; when it is determined that the identifier of the second cell is present in the second table, acquire PRACH configuration information mapped to the identifier from the second table; and attempt random access to the second cell based on the acquired PRACH configuration information.

[0207] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform: an operation of attempting the first random access multiple times, an operation of comparing the second PRACH configuration information with the first PRACH configuration information, and an operation of attempting the second random access when the identifier is determined not to be present in the second table.

[0208] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: set a validity period of the obtained PRACH configuration information to a timer value when handover from the first cell to the second cell is successful after attempting random access based on the obtained PRACH configuration information; and drive a timer having the set timer value.

[0209] The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform the following operations: checking whether there is a first history of successful initial random access to the second cell; if it is checked that there is the first history, determining whether an identifier of the second cell is in a first table; if it is determined that the identifier of the second cell is in the first table, obtaining PRACH configuration information mapped to the identifier from the first table; and determining whether PRACH configuration information used for the initial random access and the obtained PRACH configuration information are the same.

[0210] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: record the PRACH configuration information used for the initial random access in a second table if it is determined that the PRACH configuration information used for the initial random access and the obtained PRACH configuration information are different; and delete the PRACH configuration information mapped to the identifier from the first table if it is determined that the PRACH configuration information used for the initial random access and the obtained PRACH configuration information are the same.

[0211] The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform the following operations: checking whether there is a second history in which a first handover of the electronic device from the first cell to a third cell succeeds and a second handover of the electronic device from the third cell to the second cell succeeds; if it is checked that there is the second history, determining whether an identifier of the second cell is recorded in a first table; if it is determined that the identifier of the second cell is recorded in the first table, obtaining PRACH configuration information mapped to the identifier from the first table; and determining whether PRACH configuration information in a handover command that instructs the second handover is the same as the obtained PRACH configuration information.

[0212] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: record the PRACH configuration information in the handover command instructing the second handover in a second table when it is determined that the PRACH configuration information in the handover command instructing the second handover is different from the obtained PRACH configuration information; and delete the PRACH configuration information mapped to the identifier from the first table when it is determined that the PRACH configuration information in the handover command instructing the second handover is the same as the obtained PRACH configuration information.

[0213] According to one embodiment, an electronic device (101, 201, 301, 1701) may include a memory (130, 1710) for storing instructions and at least one processor (120, 210, 1720) including a processing circuit. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform an operation of receiving a handover command from a first cell, the handover command including first PRACH configuration information, for indicating a handover from the first cell to a second cell. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform an operation of determining whether an identifier of the second cell is present in a table (e.g., a second table) in which information used for random access of a successful handover of the electronic device is recorded. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to attempt a first random access to the second cell multiple times based on the first PRACH configuration information if the identifier is determined not to be in the table. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to compare the second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information if the electronic device does not receive an RAR for each of the attempted first random accesses from the second cell. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to attempt a second random access to the second cell based on the second PRACH configuration information if the second PRACH configuration information is different from the first PRACH configuration information.

[0214] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: record the first PRACH configuration information in another table (e.g., a first table) if the handover of the electronic device fails to receive an RAR for each of the attempted first random accesses from the second cell.

[0215] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: record the second PRACH configuration information in the table (e.g., the second table) if the handover of the electronic device from the first cell to the second cell is successful after attempting the second random access.

[0216] The above instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to: obtain PRACH configuration information mapped to the identifier from the table (e.g., a second table), if the identifier is determined to be in the table; and attempt random access to the second cell based on the obtained PRACH configuration information.

[0217] The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform the following operations: checking whether there is a first history of successful initial random access to the second cell; if it is checked that there is the first history, determining whether an identifier of the second cell exists in another table (e.g., a first table) in which information used for random access of a failed handover of the electronic device is recorded; if it is determined that the identifier of the second cell exists in the other table, obtaining PRACH configuration information mapped to the identifier from the other table; and determining whether the PRACH configuration information used for the initial random access and the obtained PRACH configuration information are the same.

[0218] The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to perform the following operations: checking whether there is a second history in which a first handover of the electronic device from the first cell to a third cell succeeds and a second handover of the electronic device from the third cell to the second cell succeeds; if it is checked that there is a second history, determining whether an identifier of the second cell exists in another table in which information used for a failed random access of the electronic device is recorded; if it is determined that the identifier of the second cell is recorded in the other table, obtaining PRACH configuration information mapped to the identifier from the other table; and determining whether PRACH configuration information in a handover command that instructs the second handover is the same as the obtained PRACH configuration information.

[0219] According to one embodiment, an operating method of an electronic device (101, 201, 301, 1701) may include an operation of receiving a handover command from a first cell, the handover command including first PRACH configuration information, for indicating a handover from the first cell to a second cell, an operation of attempting a first random access to the second cell multiple times based on the first PRACH configuration information, an operation of comparing the first PRACH configuration information with second PRACH configuration information in a system information message of the second cell when an RAR for each of the attempted first random accesses is not received from the second cell, and an operation of attempting a second random access to the second cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information.

[0220] The operating method of the electronic device may further include recording the first PRACH configuration information in a first table when the handover of the electronic device fails to receive an RAR for each attempted first random access from the second cell.

[0221] The operating method of the electronic device may further include recording the second PRACH configuration information in a second table when the handover of the electronic device from the first cell to the second cell is successful after attempting the second random access.

[0222] The operating method of the electronic device may further include, when the handover command is received from the first cell, an operation of determining whether an identifier of the second cell exists in a second table; when it is determined that the identifier of the second cell exists in the second table, an operation of obtaining PRACH configuration information mapped to the identifier from the second table; and an operation of attempting random access to the second cell based on the obtained PRACH configuration information.

[0223] According to one embodiment, an operating method of an electronic device may include the following actions: receiving a handover command from a first cell, the handover command instructing a handover from the first cell to a second cell, the handover command including first PRACH configuration information; determining whether an identifier of the second cell exists in a table in which information used for random access of a successful handover of the electronic device is recorded; attempting a first random access to the second cell multiple times based on the first PRACH configuration information when the identifier is determined not to be in the table; comparing second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information when an RAR for each of the attempted first random accesses is not received from the second cell; and attempting a second random access to the second cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information.

[0224] According to one embodiment, a non-transitory computer-readable recording medium may store a computer program relating to a method of operating an electronic device. The method may include: receiving a handover command from a first cell, which instructs a handover from the first cell to a second cell (the handover command may include first PRACH configuration information); attempting a first random access to the second cell multiple times based on the first PRACH configuration information; comparing second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information when an RAR for each of the attempted first random accesses is not received from the second cell; and attempting a second random access to the second cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information.

[0225] According to one embodiment, a non-transitory computer-readable recording medium may store a computer program relating to a method of operating an electronic device. The method may include: receiving a handover command from a first cell, the handover command including first PRACH configuration information, for instructing a handover from the first cell to a second cell; determining whether an identifier of the second cell exists in a table in which information used for random access of a successful handover of the electronic device is recorded; attempting a first random access to the second cell multiple times based on the first PRACH configuration information when the identifier is determined not to be in the table; comparing second PRACH configuration information in a system information message of the second cell with the first PRACH configuration information when an RAR for each of the attempted first random accesses is not received from the second cell; and attempting a second random access to the second cell based on the second PRACH configuration information when the second PRACH configuration information is different from the first PRACH configuration information.

Claims

1. In electronic devices (101, 201, 301, 1701), Memory (130, 1710) for storing commands; and At least one processor (120, 210, 1720) comprising a processing circuit Including, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: An operation of receiving a handover command from a first cell, wherein the handover command includes first PRACH (physical random access channel) configuration information, An operation of attempting a first random access to the second cell multiple times based on the first PRACH setting information; An operation of comparing the second PRACH configuration information in the system information message of the second cell with the first PRACH configuration information when the random access response (RAR) for each of the attempted first random accesses is not received from the second cell, and If the second PRACH configuration information is different from the first PRACH configuration information, an operation of attempting a second random access to the second cell based on the second PRACH configuration information. to do, Electronic devices.

2. In paragraph 1, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: If the second PRACH configuration information fails to be acquired and the handover of the electronic device fails, an operation of recording the first PRACH configuration information in the first table. to do, Electronic devices.

3. In any one of paragraphs 1 and 2, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: An operation of recording the second PRACH configuration information in a second table when the handover of the electronic device from the first cell to the second cell is successful after attempting the second random access. to do, Electronic devices.

4. In paragraph 3, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: After recording the second PRACH configuration information in the second table, an operation of receiving an additional handover command from the first cell that instructs handover from the first cell to the second cell, and If the handover according to the above additional handover command is successful, an operation of deleting the second PRACH configuration information from the second table. to do, Electronic devices.

5. In any one of paragraphs 1 to 4, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: When the handover command is received from the first cell, an operation of determining whether there is an identifier of the second cell in the second table; If it is determined that the identifier of the second cell is present in the second table, an operation of obtaining PRACH setting information mapped to the identifier from the second table, and An operation of attempting random access to the second cell based on the acquired PRACH setting information. to do, Electronic devices.

6. In paragraph 5, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: If it is determined that the identifier does not exist in the second table, an operation of attempting the first random access multiple times, an operation of comparing the second PRACH setting information with the first PRACH setting information, and an operation of attempting the second random access to perform, Electronic devices.

7. In paragraph 5, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: An operation of setting the validity period of the acquired PRACH configuration information to a timer value when handover from the first cell to the second cell is successful after attempting random access based on the acquired PRACH configuration information, and An action to drive a timer having the above set timer value to do, Electronic devices.

8. In any one of paragraphs 1 to 7, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: An operation for checking whether there is a first history of successful initial random access to the second cell; If it is checked that the above first history exists, an operation of determining whether the identifier of the second cell is in the first table; When it is determined that the identifier of the second cell is in the first table, an operation of obtaining PRACH configuration information mapped to the identifier from the first table, and An operation for determining whether the PRACH configuration information used for the initial random access is the same as the acquired PRACH configuration information. to do, Electronic devices.

9. In paragraph 8, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: If it is determined that the PRACH setting information used for the initial random access and the acquired PRACH setting information are different, an operation of recording the PRACH setting information used for the initial random access in a second table, and If it is determined that the PRACH configuration information used for the initial random access and the acquired PRACH configuration information are the same, an operation of deleting the PRACH configuration information mapped to the identifier in the first table. to do, Electronic devices.

10. In any one of paragraphs 1 to 9, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: An operation of checking whether there is a second history in which a first handover of the electronic device from the first cell to the third cell is successful and a second handover of the electronic device from the third cell to the second cell is successful; If it is checked that the second history exists, an operation of determining whether the identifier of the second cell is recorded in the first table; When it is determined that the identifier of the second cell is recorded in the first table, an operation of obtaining PRACH setting information mapped to the identifier from the first table, and An operation for determining whether the PRACH configuration information in the handover command that instructed the second handover is the same as the acquired PRACH configuration information. to do, Electronic devices.

11. In paragraph 10, The above instructions, when individually or collectively executed by the at least one processor, cause the electronic device to: If it is determined that the PRACH setting information in the handover command that instructed the second handover is different from the acquired PRACH setting information, an operation of recording the PRACH setting information in the handover command that instructed the second handover in the second table, and If it is determined that the PRACH configuration information in the handover command that instructed the second handover is the same as the acquired PRACH configuration information, an operation of deleting the PRACH configuration information mapped to the identifier in the first table. to do, Electronic devices.

12. In the operating method of an electronic device (101, 201, 301, 1701), An operation of receiving a handover command from a first cell, the handover command including first PRACH configuration information, for instructing handover from the first cell to a second cell; An operation of attempting a first random access to the second cell multiple times based on the first PRACH setting information; An operation of comparing the second PRACH configuration information in the system information message of the second cell with the first PRACH configuration information when the RAR for each attempted first random access is not received from the second cell; and If the second PRACH configuration information is different from the first PRACH configuration information, an operation of attempting a second random access to the second cell based on the second PRACH configuration information. including, How an electronic device operates.

13. In paragraph 12, An operation of recording the first PRACH configuration information in the first table when the handover of the electronic device fails because the RAR for each attempted first random access is not received from the second cell. including more, How an electronic device operates.

14. In any one of paragraphs 12 to 13, An operation of recording the second PRACH configuration information in a second table when the handover of the electronic device from the first cell to the second cell is successful after attempting the second random access. including more, How an electronic device operates.

15. In any one of paragraphs 12 to 14, An operation of determining whether an identifier of the second cell exists in a second table when the handover command is received from the first cell; If it is determined that the second cell identifier is present in the second table, an operation of obtaining PRACH configuration information mapped to the identifier from the second table; and An operation of attempting random access to the second cell based on the acquired PRACH setting information. including more, How an electronic device operates.

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