EP-4738927-A1 - ELECTRONIC DEVICE IN NON-TERRESTRIAL NETWORK, AND METHOD

EP4738927A1EP 4738927 A1EP4738927 A1EP 4738927A1EP-4738927-A1

Abstract

The present disclosure relates to an electronic device in a non-terrestrial network, and a method. Described is an electronic device used for a first base station in a non-terrestrial network, and the non-terrestrial network further comprises a user equipment, a second base station, a network function and a satellite, which can communicate with the first base station. The electronic device comprises a processing circuit, which is configured to enable a first base station to execute the following operations: on the basis of a message received from a network function, determining to initiate a first handover of a user equipment to a second base station at a first time; sending a handover request message to the second base station, wherein the handover request message indicates that the handover type of the first handover is a base-station-initiated type; and in response to having received a message indicating that the second base station accepts a handover request, sending a handover command to the user equipment, wherein the handover command instructs the user equipment to execute the first handover, and indicates that the handover type of the first handover is the base-station-initiated type.

Inventors

WANG, Xiaoxue
SUN, CHEN
ZHOU, Mingtuo

Assignees

Sony Group Corporation

Dates

Publication Date: 20260506
Application Date: 20240627

Claims (20)

An electronic device for a first base station in a non-terrestrial network, wherein the non-terrestrial network further comprises a user equipment device capable of communicating with the first base station, a second base station, a network function, and a satellite, the electronic device comprising a processing circuit configured to cause the first base station to perform following operations: determining, based on a message received from the network function, that a first handover of the user equipment device to the second base station is to be initiated at a first time; transmitting a handover request message to the second base station, wherein the handover request message indicates that a handover type of the first handover is a base station-initiated type; and transmitting a handover command to the user equipment device, in response to receiving a message indicating that the second base station has accepted the handover request, wherein the handover command instructs the user equipment device to perform the first handover and indicates that the handover type of the first handover is the base station-initiated type.
The electronic device according to claim 1, wherein the processing circuit is further configured to cause the first base station to perform following operations: receiving a measurement report from the user equipment device, wherein the measurement report indicates that at least one of a signal quality between the user equipment device and the first base station or a signal quality between the user equipment device and the second base station does not meet a predefined condition; transmitting to the second base station a message indicating to stop the first handover; and transmitting to the user equipment device a message indicating to stop the first handover and to change the handover type to a user equipment device-initiated type.
The electronic device according to claim 1, wherein the processing circuit is further configured to cause the first base station to perform following operations: after completion of the first handover, transmitting handover data of the first handover to the network function.
The electronic device according to any of claims 1 to 3, wherein the processing circuit is further configured to cause the first base station to perform following operations: transmitting to the user equipment device a message indicating to change the handover type to a user equipment device-initiated type, in response to receiving a message indicating that the second base station has rejected the handover request.
The electronic device according to any of claims 1 to 3, wherein transmitting the handover request message to the second base station comprises: transmitting the handover request message directly to the second base station, or transmitting a handover requirement to the network function, wherein a type of the handover requirement is configured as the base station-initiated type, and wherein the handover request message is transmitted to the second base station by the network function in response to receiving the handover requirement.
The electronic device according to any of claims 1 to 3, wherein the message indicating that the second base station has accepted the handover request is an acknowledgement message for the handover request received from the second base station or a handover command received from the network function.
The electronic device according to any of claims 1 to 3, wherein the message received from the network function comprises handover model parameters, wherein the handover model parameters comprise at least an identifier of the user equipment device, a set of handover times comprising the first time, an identifier of the first base station, and an identifier of the second base station.
The electronic device according to claim 7, wherein the user equipment device is a location-fixed type user equipment device, and the processing circuit is further configured to cause the first base station to perform following operations: prior to the first handover, receiving from the network function a message instructing the first base station to collect handover data for a set of location-fixed type user equipment devices comprising the user equipment device; performing a first plurality of handovers of user equipment device-initiated type with user equipment devices in the set of location-fixed type user equipment devices; and transmitting handover data of the first plurality of handovers to the network function, wherein the first plurality of handovers occur prior to the first handover, wherein the handover model parameters are obtained by the network function based on the handover data of the first plurality of handovers.
The electronic device according to claim 7, wherein the processing circuit is further configured to cause the first base station to perform following operations: after receiving the handover model parameters from the network function, performing a second plurality of handovers of user equipment device-initiated type with the user equipment device; transmitting handover data of the second plurality of handovers to the network function, wherein the second plurality of handovers occur prior to the first handover; and receiving from the network function a message indicating that a handover of base station-initiated type can begin, wherein determining to initiate the first handover of the user equipment device to the second base station at the first time is performed at least in response to receiving the message indicating that the handover of base station-initiated type can begin.
The electronic device according to claim 8 or 9, wherein the handover data comprises one or more of: an identifier of a user equipment device associated with a handover, a time to initiate the handover determined by a source base station associated with the handover, a signal quality between the user equipment device and the source base station and a signal quality between the user equipment device and a target base station associated with the handover reported by the user equipment device based on which the source base station determines to initiate the handover, an identifier of the source base station, an identifier of the target base station, an identifier of a satellite associated with the source base station, an identifier of a satellite associated with the target base station, and weather conditions.
The electronic device according to claim 8, wherein the handover model parameters are obtained by the network function through following operations: training a machine learning model using the handover data of the first plurality of handovers as training data; and generating the handover model parameters by inputting the identifier of the user equipment device into the trained machine learning model.
An electronic device for a base station in a non-terrestrial network, wherein the non-terrestrial network further comprises a user equipment device capable of communicating with the base station, a network function, and a satellite, the electronic device comprising a processing circuit configured to cause the base station to perform following operations: receiving a registration request message from the user equipment device, wherein the registration request message comprises a location type bit indicating whether the user equipment device is of a location-fixed type or a location-mobile type; transmitting the registration request message to the network function; and based on an acknowledgement for the registration request message received from the network function, transmitting a registration accept message to the user equipment device, wherein, in response to the location type bit indicating that the user equipment device is of the location-fixed type, the registration accept message comprises information indicating that a handover type for the user equipment device is configured as base station-initiated.
The electronic device according to claim 12, wherein when the location type bit indicates that the user equipment device is of the location-fixed type, the registration request message further comprises a field indicating geographical location information of the user equipment device.
An electronic device for a user equipment device in a non-terrestrial network, wherein the non-terrestrial network further comprises a first base station capable of communicating with the user equipment device, a second base station capable of communicating with the first base station, a network function, and a satellite, the electronic device comprising a processing circuit configured to cause the user equipment device to perform following operations: receiving a handover command from the first base station, wherein the handover command instructs the user equipment device to perform a first handover to the second base station and indicates that a handover type of the first handover is a base station-initiated type; performing signal quality measurements with the first base station and signal quality measurements with the second base station within a predetermined time period; and performing the first handover in response to determining that, within the predetermined time period, a signal quality between the user equipment device and the first base station and a signal quality between the user equipment device and the second base station meet a predefined condition.
The electronic device according to claim 14, wherein: the first base station determines to initiate the first handover at a first time based on a message received from the network function; the first base station transmits a handover request message to the second base station, wherein the handover request message indicates that the handover type of the first handover is the base station-initiated type; and the handover command is transmitted by the first base station to the user equipment device in response to receiving a message indicating that the second base station has accepted the handover request.
The electronic device according to claim 14 or 15, wherein the processing circuit is further configured to cause the user equipment device to perform following operations: in response to determining that, within the predetermined time period, at least one of the signal quality between the user equipment device and the first base station or the signal quality between the user equipment device and the second base station does not meet the predefined condition: transmitting a measurement report to the first base station; receiving from the first base station a message indicating to stop the first handover and to change the handover type to a user equipment device-initiated type; and performing signal quality measurements with the first base station and signal quality measurements with one or more base stations comprising the second base station.
The electronic device according to claim 15, wherein the processing circuit is further configured to cause the user equipment device to perform following operations: receive from the first base station a message indicating to change the handover type to a user equipment device-initiated type, wherein the message is transmitted to the user equipment device by the first base station in response to receiving a message indicating that the second base station has rejected the handover request.
The electronic device according to claim 15, wherein the first base station transmitting the handover request message to the second base station comprises: the first base station transmitting the handover request message directly to the second base station, or the first base station transmitting a handover requirement to the network function, wherein a type of the handover requirement is configured as the base station-initiated type, and wherein the handover request message is transmitted to the second base station by the network function in response to receiving the handover requirement.
The electronic device according to claim 15, wherein the message indicating that the second base station has accepted the handover request is an acknowledgement message for the handover request received by the first base station from the second base station, or a handover command received by the first base station from the network function.
The electronic device according to claim 15, wherein the message received by the first base station from the network function comprises handover model parameters, wherein the handover model parameters comprise at least an identifier of the user equipment device, a set of handover times comprising the first time, an identifier of the first base station, and an identifier of the second base station.

Description

TECHNICAL FIELD The present disclosure generally relates to devices and methods in a non-terrestrial network (NTN), and specifically relates to techniques for cell handover in the non-terrestrial network. BACKGROUND Wireless communication systems can utilize various protocols and standards for data transmission between devices. These protocols and standards have undergone extensive development over time, including but not limited to the Third Generation Partnership Project (3GPP), the 3GPP Long Term Evolution (LTE) (e.g., 4G communications), and 3GPP New Radio (NR) (e.g., 5G communications), and even 6G communications. Compared to traditional wireless communication systems, new wireless communication systems (such as 5G NR communication systems, 6G communication systems) significantly enhance speed, latency, capacity, flexibility, and reliability of wireless transmission, thereby providing more possibilities for new usage scenarios. New wireless communication systems introduce non-terrestrial network communication involving high-altitude platforms such as satellites, serving as a supplement to performance of terrestrial network communications. For example, mobile operators can utilize non-terrestrial networks to provide wireless communication services to areas lacking infrastructure and can continue to offer normal wireless communication services in case of terrestrial network interruptions (such as in battlefield, earthquake or flood, outdoor scenarios). In a non-terrestrial network, frequent cell handovers might be needed. For example, a low earth orbit (LEO) satellite typically operates at altitudes between 200 kilometers and 2,000 kilometers from the earth. When the LEO satellite is closer to the earth, such as at an altitude of 600 kilometers or 1,200 kilometers, the diameter of the satellite beam's projection on the ground might be relatively small. For example, at an altitude of 600 kilometers and a frequency band of 20GHz, the beam's projection coverage diameter on the ground is about 50 kilometers, with a maximum beam coverage diameter of approximately 1,000 kilometers. Additionally, because the LEO satellite moves at high speeds relative to the ground, the emitted beam's projection also moves rapidly on the ground, with speeds ranging between 6.5 kilometers per second and 8.1 kilometers per second. If a user equipment device is on a high-speed moving airplane, traveling at a speed of 1,000 kilometers per hour, and if the airplane is moving in the same direction as the satellite, the time to cover the user equipment device would be 6.51 seconds or 130 seconds for a beam coverage diameter of 50 kilometers or 1,000 kilometers respectively. If the airplane is moving in the opposite direction to the satellite, the time would be 6 seconds or 120 seconds respectively. This means that the user equipment device needs to perform cell handover every approximately 6 seconds, up to every approximately 130 seconds, at the longest. Therefore, there is a need to find devices and methods that can improve cell handover in the non-terrestrial networks. SUMMARY The present disclosure presents devices and methods in non-terrestrial networks. According to a first aspect of the present disclosure, an electronic device for a first base station in a non-terrestrial network is provided. The non-terrestrial network further includes a user equipment device capable of communicating with the first base station, a second base station, a network function, and a satellite. The electronic device includes a processing circuit configured to cause the first base station to perform following operations: determining, based on a message received from the network function, that a first handover of the user equipment device to the second base station is to be initiated at a first time; transmitting a handover request message to the second base station, wherein the handover request message indicates that a handover type of the first handover is the base station-initiated type; and transmitting a handover command to the user equipment device, in response to receiving a message indicating that the second base station has accepted the handover request, wherein the handover command instructs the user equipment device to perform the first handover and indicates that the handover type of the first handover is a base station-initiated type. Correspondingly, according to the first aspect of the present disclosure, a method for a first base station in a non-terrestrial network is provided. The non-terrestrial network further includes a user equipment device capable of communicating with the first base station, a second base station, a network function, and a satellite. The method includes: determining, based on a message received from the network function, that a first handover of the user equipment device to the second base station is to be initiated at a first time; transmitting a handover request message to the second base station, wherein the h