How to update the tracking area and terminal devices

Abstract

This invention provides a method and terminal device for updating the tracking area, which is advantageous in reducing the power consumption of terminal devices and mitigating the ping-pong effect problem. [Solution] The method includes the following steps: Obtain the geographical location of the terminal device. The terminal device uses non-terrestrial network (NTN) communication functionality. Determine the first tracking area where the terminal device is located based on its geographical location. If it is determined that a Tracking Area Update (TAU) procedure needs to be performed, in response, send a request message to the network device, the request message indicating the first tracking area.

Description

Technical Field

[0001] The present invention relates to communication technologies, and particularly to a method for updating a tracking area and a terminal device.

Background Art

[0002] 3GPP (registered trademark) has established multiple communication standards. Among them, the registration request and the tracking area update (TAU) request messages play important roles in network registration and connection maintenance.

[0003] Referring to FIG. 1, FIG. 1 is a schematic diagram of a non-access stratum (NAS) registration mechanism in a fifth-generation communication system. In FIG. 1, when a user equipment (UE) first registers with a network, a registration request message is sent to an access and mobility management function (AMF) entity. The registration request message includes the UE's identification information (e.g., international mobile equipment identity (IMEI) and international mobile subscriber identity (IMSI)) and network capabilities (e.g., supported frequency bands and services), ensuring that the UE is correctly identified and authenticated by the network.

[0004] A registration accept message returned by the network can indicate that the registration request message was successfully received by the network and may also indicate a list of tracking area identifiers (TAIs) configured to show the tracking area corresponding to the UE.

[0005] Referring to Figure 2, which is a schematic diagram of a TAI list, the TAI list can include a public land mobile network identifier (PLMN ID) and a tracking area code (TAC). The PLMN ID is configured to identify the network operator and typically consists of a 12-bit mobile country code (MCC) and an 8-bit or 12-bit mobile network code (MNC). The TAC (16 bits) identifies a specific tracking area within the network.

[0006] When a UE moves to a new tracking area and the TAC for that tracking area is not in the TAI list, the UE can initiate a TAU request message to notify the network that its current location has changed. The network then responds with a TAU acceptance message to update the TAI list and track and manage the UE's location.

[0007] Referring to Figure 3, which is a schematic diagram of the TAU, we assume that the UE's TAI list includes TAC-1 and TAC-2. In this situation, if the UE moves from geographical region 311 corresponding to TAC-1 to geographical region 312 corresponding to TAC-2, the TAU is not triggered. However, if the UE moves to geographical region 313 corresponding to TAC-3, the TAU is triggered because TAC-3 is not in the TAI list. [Overview of the project] [Problems that the invention aims to solve]

[0008] However, when applied to non-terrestrial networks (NTN), existing TAU procedures may face the following challenges.

[0009] (1) Frequent TAU ​​triggering: NTN satellites operate in low Earth orbit (LEO) and travel at a speed of approximately 27,000 kilometers per hour. When switching between different satellites, the UE may frequently trigger TAU, resulting in increased load on the core network and increased battery consumption of devices.

[0010] (2) Ping-pong effect: NTN satellites operate at altitudes of approximately 500 to 1200 kilometers. Taking a satellite at an altitude of 500 kilometers as an example, the maximum diameter of its coverage area is approximately 5,064 kilometers. Therefore, NTN needs to consist of multiple satellites to achieve uninterrupted service. However, in boundary areas where satellite coverage overlaps, the ping-pong effect can occur as devices frequently switch between satellites. [Means for solving the problem]

[0011] Based on this, the present invention provides a method for updating a tracking area configured to solve the above technical problems, and a terminal device.

[0012] The present invention provides a method for updating a tracking area. This method includes the following steps: A terminal device obtains its geographical location, and the terminal device uses a non-terrestrial network communication function. The terminal device determines a first tracking area, and the terminal device is located based on its geographical location. When it determines that it is necessary to perform a tracking area update procedure, the terminal device responds by sending a request message to a network device, and the request message indicates the first tracking area.

[0013] The present invention provides a terminal device including a transceiver and a processor. The processor is coupled to the transceiver and is configured to obtain the geographical location of the terminal device, determine that the terminal device is using a non-terrestrial network communication function, determine a first tracking area where the terminal device is located based on its geographical location, and, if it determines that a tracking area update procedure needs to be performed, control the transceiver to send a request message to a network device in response, the request message indicating the first tracking area. [Effects of the Invention]

[0014] As described above, the embodiments of the present invention are advantageous in reducing the power consumption of the terminal device and mitigating the ping-pong effect problem because the timing of initiating the TAU procedure can be determined by the terminal device. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram of the Non-Access Layer (NAS) registration mechanism in a fifth-generation communication system. [Figure 2] This is a schematic diagram of the TAI list. [Figure 3] This is a schematic diagram of TAU. [Figure 4] This is a schematic diagram of a terminal device according to one embodiment of the present invention. [Figure 5]This is a flowchart of a method for updating a tracking area according to one embodiment of the present invention. [Figure 6] This is a flowchart of a method for updating the tracking area according to the third embodiment of the present invention. [Figure 7] This is a schematic diagram of an application scenario according to one embodiment of the present invention. [Figure 8] This is a schematic diagram of an application scenario according to one embodiment of the present invention. [Modes for carrying out the invention]

[0016] Referring to Figure 4, Figure 4 is a schematic diagram of a terminal device according to one embodiment of the present invention. In different embodiments, the terminal device 400 can be configured to implement various communication devices such as UEs.

[0017] In Figure 4, the terminal device 400 includes a transceiver 402 and a processor 404. The transceiver 402 can be configured to send and receive signals from other devices within its coverage range. The transceiver 402 can perform analog-to-digital signal conversion (ADC), digital-to-analog signal conversion (DAC), modulation, demodulation, signal amplification, low-pass filtering, and band-pass filtering. For example, the transceiver 402 may be configured to provide information about a received signal to the processor 404, modulate the data received from the processor 404 into a modulated signal, and transmit that modulated signal to other devices.

[0018] In some embodiments, the terminal device 400 may further include other elements, such as an antenna module for performing the functions of the transceiver 402 and processor 404 described above.

[0019] Processor 404 can be coupled to transceiver 402. Processor 404 can be, for example, a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, other types of integrated circuit (IC), and a state machine.

[0020] In an embodiment of the present invention, terminal device 400 is, for example, a communication device that uses NTN communication function.

[0021] In some embodiments, terminal device 400 is, for example, a device configured to communicate with a network device, and generally, a mobile device owned by a user, such as a smartphone, a tablet computer, an Internet of Things (IoT) device, a satellite phone, or a drone. These devices can transmit and receive data in a wireless network and implement various applications and services.

[0022] Terminal device 400 having NTN communication function does not depend only on a conventional terrestrial mobile network (e.g., a 4G / 5G base station) and can communicate with a non-terrestrial infrastructure. With this function, the device can communicate with a satellite (LEO, MEO, or GEO), a high altitude platform system (HAPS) (e.g., a high altitude balloon or a drone).

[0023] To implement NTN communication functions, the terminal device 400 requires specific hardware and software support, such as a dedicated antenna capable of supporting satellite frequency bands (Ka-band, Ku-band, and S-band, etc.), while high-performance modulation and coding techniques can cope with high latency and signal attenuation. Furthermore, the terminal device 400 can be equipped with a positioning circuit to implement precise positioning functions for tracking the location of satellites and NTN platforms.

[0024] In different embodiments, network devices communicating with terminal device 400 include various types of satellites and HAPS. Satellites are mainly classified into low Earth orbit (LEO) satellites, medium Earth orbit (MEO) satellites, and geostationary orbit (GEO) satellites. HAPS include, but are not limited to, high-altitude balloons and unmanned aerial vehicles (e.g., solar-powered unmanned aerial vehicles).

[0025] In one embodiment, the terminal device 400 can use the NTN communication function by, for example, enabling the NTN communication application. The terminal device 400 is, for example, a smartphone with the NTN communication application installed, and when the user of the terminal device 400 wants to use the NTN communication function, the NTN communication application can be enabled accordingly, allowing the terminal device 400 to use the NTN communication function. However, the present invention is not limited to this.

[0026] In embodiments of the present invention, transmission / reception of the terminal device 400 can be performed by the processor 402 controlling the transceiver 404.

[0027] In embodiments of the present invention, the processor 404 can implement the method for updating the tracking area proposed by the present invention by accessing the relevant modules and code. Details thereof are described below.

[0028] Referring to Figure 5, Figure 5 is a flowchart of a method for updating a tracking area according to one embodiment of the present invention. The method of this embodiment can be performed by the terminal device 400 shown in Figure 4. Details of each step in Figure 5 will be described below in conjunction with the elements shown in Figure 4.

[0029] In step S510, the processor 404 obtains the geographical location (hereinafter referred to as location LO) of the terminal device 400.

[0030] In one embodiment, the processor 404 may obtain the current location of the terminal device 400 as the geographic location LO considered in step S510, for example, by a global positioning system (GPS) module or other similar positioning circuit, but the present invention is not limited thereto.

[0031] In step S520, the processor 404 determines the first tracking area where the terminal device 400 is located based on the geographical location LO.

[0032] In one embodiment, an NTN communications application can record multiple preset tracking areas.

[0033] In some embodiments, the preset tracking area may be, for example, multiple geographical areas distributed within the coverage area of ​​the NTN service used by the terminal device 400, and each preset tracking area is configured with a corresponding TAC.

[0034] In one embodiment, the processor 404 can determine whether the geographic location LO is in one of the preset tracking areas. If it determines that the geographic location LO is in a first preset area of ​​the preset tracking areas, the processor 404 can then determine that the first preset area is the first tracking area considered in step S520.

[0035] In embodiments of the present invention, the processor 404 can determine whether it is necessary to perform a TAU procedure.

[0036] In the first embodiment, the processor 404 can determine whether it is necessary to perform the TAU procedure by determining whether the terminal device 400 is in the registration stage of the NTN communication function.

[0037] For example, if a user has just launched an NTN communication application, the terminal device 400 may not yet be registered with the corresponding network device. In this situation, the processor 404 can determine that the terminal device 400 is in the registration stage for the NTN communication function, and vice versa.

[0038] As another example, in some embodiments, the processor 404 may determine that the terminal device 400 is in the registration phase for NTN communication functions, unless the processor 404 has not yet notified the corresponding network device of the tracking area in which the terminal device 400 is located, but the present invention is not limited thereto.

[0039] In the first embodiment, when it is determined that the terminal device 400 is in the registration stage for the NTN communication function, the processor 404 can determine in response that it is necessary to execute the TAU procedure.

[0040] In the second embodiment, the processor 404 can determine whether it is necessary to perform the TAU procedure by determining whether the first tracking area terminal and the tracking area where the device 400 was previously located (hereinafter referred to as the second tracking area) are the same.

[0041] In the second embodiment, the second tracking area is, for example, the tracking area where the terminal device 400 was located when it was last notified to the network device. That is, the network device knows that the terminal device 400 is currently located in the second tracking area.

[0042] In the second embodiment, if it is determined that the first tracking area and the second tracking area where the terminal device 400 was previously located are different, the processor 404 may, in response, determine that it is necessary to perform a TAU procedure.

[0043] In other words, when the processor 404 determines that the first tracking area where the terminal device 400 is currently located is different from the second tracking area previously notified to the network device, the processor 404 may determine that it is necessary to perform a TAU procedure, but the present invention is not limited thereto.

[0044] In another embodiment, if it is determined that the first tracking area and the second tracking area where the terminal device 400 was previously located are the same, the processor 404 may, in response, determine that it is not necessary to perform the TAU procedure.

[0045] In a third embodiment, when the processor 404 determines that the terminal device 400 is not in the registration stage for NTN communication functions as in the first embodiment, the processor 404 may have previously notified the network device of the tracking area in which the terminal device 400 is located. In this situation, the processor 404 may proceed to perform the means of the second embodiment, but the present invention is not limited thereto.

[0046] In step S530, if it is determined that the TAU procedure needs to be performed, the processor 404 responds by controlling the transceiver 402 to send a request message (hereinafter referred to as M1) to the network device. Here, the request message M1 indicates the first tracking area.

[0047] In one embodiment, request message M1 may indicate the TAC of a first tracking area, and hereafter we will assume that the TAC of the first tracking area is "TAC1", but the present invention is not limited thereto.

[0048] In the first embodiment, the processor 404 can control the transceiver 402 to send a registration request corresponding to the NTN communication function as a request message M1 to the network device. In one embodiment, the above-described registration request may have, for example, the contents shown in Table 1 below.

[0049] [Table 1]

[0050] As can be seen from Table 1, compared to known registration requests, the registration request proposed in this embodiment of the present invention further includes a TAI list. That is, unlike existing technologies in which the network provides the TAI list, this embodiment of the present invention allows the terminal device 400 to provide the TAI list to the network device via the registration request, but the present invention is not limited thereto.

[0051] In a second embodiment, the processor 404 can control the transceiver 402 to send the TAU request message as request message M1 to the network device. In one embodiment, the TAU request message described above may have, for example, the contents shown in Table 2 below.

[0052] [Table 2]

[0053] As can be seen from Table 1, compared to known TAU request messages, the TAU request message proposed in this embodiment of the present invention further includes a TAI list. That is, unlike existing technologies in which the network provides the TAI list, this embodiment of the present invention allows the terminal device 400 to provide the TAI list to the network device via the TAU request message, but the present invention is not limited thereto.

[0054] In one embodiment, after receiving a request message M1, the network device may respond by sending a response message to the terminal device 400. Hereinafter, the response message may indicate that the terminal device 400 has completed its TAU procedure.

[0055] In the first embodiment, where the request message M1 is a registration request, the response message may be, for example, an acceptance registration message that does not indicate any tracking area.

[0056] In the second embodiment, where the request message M1 is a TAU request message, the response message may be, for example, an acceptance TAU message that does not indicate any tracking area.

[0057] As can be seen from above, unlike existing methods in which a network device responds to a TAU request message from a UE by providing the UE with an updated TAI list, the technical solution of this embodiment of the present invention allows a terminal device 400 having NTN communication capabilities to notify a network device of the first tracking area in which it is currently located via a request message M1 (e.g., a registration request and / or a TAU request message) when it determines that it is necessary to initiate a TAU procedure.

[0058] This allows the terminal device 400 to determine when to initiate the TAU procedure. In this situation, when the terminal device 400 is stationary or not moving to a new tracking area, the TAU is not triggered by changes in satellite coverage, thus helping to reduce the power consumption of the terminal device 400.

[0059] Furthermore, since the terminal device 400 can accurately acquire its geographical location LO (for example, the GPS location of the terminal device 400), the processor 404 can accurately determine the tracking area in which the terminal device 400 is located, thereby mitigating the ping-pong effect problem.

[0060] Referring to Figure 6, Figure 6 is a flowchart of a method for updating the tracking area according to the third embodiment of the present invention. The method of this embodiment can be performed by the terminal device 400 shown in Figure 4. Details of each step in Figure 6 will be described below in conjunction with the components shown in Figure 4.

[0061] In step S610, the processor 404 obtains the geographical location LO of the terminal device 400. In step S620, the processor 404 determines the first tracking area where the terminal device 400 is located based on the geographical location LO. Details of steps S610 and S620 can be found in the related explanations of steps S510 and S520, so they will not be repeated here.

[0062] In step S630, the processor 404 can determine whether the terminal device 400 is in the registration stage for the NTN communication function.

[0063] If the determination is "Yes", the processor 404 can proceed to step S640 and send a registration request corresponding to the NTN communication function as request message M1 to the network device. The processor 404 can then return to step S610 and continue to monitor whether the geographic location of the terminal device 400 has been changed to correspond to another tracking area.

[0064] In another embodiment, if the processor 404 determines in step S630 that the terminal device 400 is not in the registration stage for the NTN communication function, the processor 404 has previously notified the network device of the tracking area where the terminal device 400 is located (for example, the second tracking area described above). In this situation, the processor 404 can proceed to step S650 and determine whether the first tracking area and the second tracking area where the terminal device 400 was previously located are the same.

[0065] If the determination is "Yes," there is no need to perform the TAU procedure, so the processor 404 can return to step S610 and continue to monitor whether the geographic location of the terminal device 400 has changed to correspond to another tracking area.

[0066] In another embodiment, if the processor 404 determines in step S650 that the first tracking area and the second tracking area where the terminal device 400 was previously located are different, the terminal device 400 moves to the new tracking area. In this situation, the processor 404 can perform step S660 and send a TAU request message to the network device as request message M1. The processor 404 can then return to step S610 and continue to monitor whether the geographical location of the terminal device 400 has changed to correspond to the other tracking area, but the present invention is not limited thereto.

[0067] Referring to Figure 7, Figure 7 is a schematic diagram of an application scenario according to one embodiment of the present invention.

[0068] In Figure 7, Scenario 1 is, for example, a known TAU mechanism. In Scenario 1, TAC1 and TAC2 are defined based on the signal coverage of different satellites, so there may be an overlap area 710 of several kilometers between TAC1 and TAC2. When the terminal device 400 is located in the overlap area 710, the ping-pong effect described above may occur.

[0069] Furthermore, Scenario 2 is, for example, the mechanism proposed in the embodiment of the present invention. In Scenario 2, TAC1 and TAC2 are distinguished by their geographical location / area, so that there is no overlapping area between TAC1 and TAC2, thereby preventing the ping-pong effect described above from occurring in the terminal device 400.

[0070] Referring to Figure 8, which is a schematic diagram of an application scenario according to one embodiment of the present invention. In this embodiment, when the NTN communication function is activated while located in the tracking area 801, the terminal device 400 can determine its current location in the tracking area 801 after obtaining its current geographic location. Subsequently, the terminal device 400 can send a registration request corresponding to the NTN communication function to the network device 821 (e.g., satellite) as a request message M11. Here, the request message M11 may indicate the TAC of the tracking area 801 (e.g., "TAC1").

[0071] In this situation, the request message M11 may have, for example, the format shown in Table 1, and the TAI list may include MCC, MNC, and TAC1, but the present invention is not limited thereto.

[0072] In response, after receiving the request message M11, the network device 821 may send back a response message indicating that the terminal device 400's TAU procedure is complete (for example, an acceptance registration message that does not indicate any tracking area).

[0073] Furthermore, after moving to tracking area 802, terminal device 400 can determine its current location within tracking area 802 after obtaining its current geographical location. In this situation, since terminal device 400 is no longer in the NTN communication function registration stage, terminal device 400 can send a TAU request message as request message M12 to network device 822 when it determines that the current tracking area 802 is different from the previous tracking area 801. Here, request message M12 may indicate the TAC of tracking area 802 (for example, "TAC2").

[0074] In this situation, the request message M12 may have, for example, the format shown in Table 2, and the TAI list may include MCC, MNC, and TAC2, but the present invention is not limited thereto.

[0075] In response, after receiving the request message M12, the network device 821 may send back a response message indicating that the terminal device 400's TAU procedure is complete (for example, an accepted TAU message that does not indicate any tracking area).

[0076] As described above, the method proposed in the embodiments of the present invention enables a terminal device using NTN communication functionality to notify a network device of the tracking area in which it is currently located via a request message (e.g., a registration request and / or a TAU request message) when it determines that it needs to initiate a TAU procedure.

[0077] This allows the terminal device to determine when to initiate the TAU procedure, which is advantageous in reducing the terminal device's power consumption and mitigating the ping-pong effect problem.

[0078] Although the present invention has been disclosed in the embodiments described above, these embodiments are not intended to limit the invention. Those skilled in the art can make several changes and modifications without departing from the spirit and scope of the invention. Accordingly, the scope of protection of the present invention shall be defined by the appended claims. [Industrial applicability]

[0079] The method for updating the tracking area and the terminal devices can be applied to the TAU procedure of a 5G communication system. [Explanation of Symbols]

[0080] 311~313 Geographical area 400 terminal devices 402 Transceiver 404 Processor S510, S520, S530, S610, S620, S630, S640, S650, S660 Step M11, M12 request messages 710 Overlapping Areas Tracking areas 801 and 802 821, 822 Network Devices

Claims

1. The geographical location of the terminal device is obtained by using a terminal device that uses a non-terrestrial network (NTN) communication function, The terminal device determines the first tracking area where the terminal device is located based on the geographical location, When it is determined that a Tracking Area Update (TAU) procedure needs to be performed, the terminal device responds by sending a request message indicating the first tracking area to the network device. How to update the tracking area, including the area.

2. The terminal device is determined to be in the registration stage of the NTN communication function, When the terminal device determines that it is in the registration stage of the NTN communication function, it determines in response that it is necessary to execute the TAU procedure, and the terminal device sends a registration request corresponding to the NTN communication function as a request message to the network device. When it is determined that the first tracking area and the second tracking area where the terminal device was previously located are different, it is determined in response that it is necessary to perform the TAU procedure, and the terminal device sends a TAU request message to the network device as the request message. A method for updating a tracking area according to claim 1, further comprising:

3. The further includes receiving a response message from the network device indicating that the TAU procedure of the terminal device has been completed, corresponding to the request message. A method for updating a tracking area according to claim 1, wherein the request message is a registration request corresponding to the NTN communication function, and the response message is an accepted registration message that does not indicate any tracking area, or the request message is a TAU request message, and the response message is an accepted TAU message that does not indicate any tracking area.

4. The aforementioned terminal device further includes using the NTN communication function by enabling an NTN communication application that records multiple preset tracking areas, The plurality of preset tracking areas include a first preset area, and the determination of the first tracking area where the terminal device is located based on the geographical location is as follows: If it is determined that the geographical location is within the first preset area, the system includes determining in response that the first preset area is the first tracking area. A method for updating a tracking area according to claim 1, wherein the request message indicates the tracking area code of the first tracking area.

5. Terminal device, Transceiver and, Coupled to the aforementioned transceiver, To obtain the geographical location of the terminal device using NTN communication functionality, Based on the aforementioned geographical location, the first tracking area in which the terminal device is located is determined, When it is determined that a TAU procedure needs to be performed, the transceiver is controlled to send a request message indicating the first tracking area to the network device in response. A processor configured to perform the following: Terminal devices including these.

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