Network node of mobile communication network and computer program
By determining handover types based on control packet conditions, the network node optimizes handover paths in mobile communication networks, reducing latency and jitter for wireless devices, thus improving network performance.
Patent Information
- Application Number
- JP2024010258
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-01-26
- Publication Date
- 2025-08-07
AI Technical Summary
In mobile communication networks where core network functions are deployed in a central site geographically different from edge sites, handovers (HO) may result in suboptimal control signaling paths, leading to increased latency for wireless devices (WDs) even when core network functions are deployed at edge sites due to prioritization of inter-gNB HO over inter-AMF HO.
A network node comprising an acquisition means to gather control conditions from a wireless device and a determination means to select an appropriate handover type based on the satisfaction of delay and jitter conditions for control packets through both inter-gNB and inter-AMF paths, ensuring the selected handover type meets the device's requirements.
This approach allows for the appropriate control of handover types, ensuring that wireless devices experience reduced latency and jitter in control signaling by selecting handover paths that meet their specified conditions, thereby enhancing network performance.
Smart Images
Figure 2025115683000001_ABST
Abstract
Description
[Technical Field]
[0001] The present disclosure relates to handover techniques in mobile communication systems. [Background technology]
[0002] FIG. 1 is an explanatory diagram of handover (HO) types defined by the 3rd Generation Partnership Project (3GPP (registered trademark)). Note that an interface connecting an Access and Mobility Management Function (AMF) and a base station (gNB) is referred to as an N2 interface. An interface connecting two AMFs is referred to as an N14 interface. An interface connecting two gNBs is referred to as an Xn interface. According to FIG. 1, AMF#1 is connected to gNB#1 and gNB#2 via the N2 interface, and AMF#2 is connected to gNB#3 via the N2 interface. Furthermore, AMF#1 and AMF#2 are connected via the N14 interface, and gNB#1 and gNB#2 are connected via the Xn interface.
[0003] For example, when a wireless device (WD) connected to gNB#1 is handed over to gNB#2, if gNB#1 and gNB#2 are connected via an Xn interface, inter-gNB Xn HO using the Xn interface is performed preferentially. If gNB#1 and gNB#2 are not connected via an Xn interface, inter-gNB N2 HO using the N2 interface connected to gNB#2 is performed. Furthermore, when a wireless device (WD) connected to gNB#2 is handed over to gNB#3, inter-AMF HO is performed, which involves changing the AMF that manages the WD. Note that inter-gNB Xn HO and inter-gNB N2 HO have different control signaling paths during HO, but after HO, control signaling is transmitted and received in both cases via the N2 interface between the gNB and AMF after HO. In the following description, inter-gNB Xn HO and inter-gNB N2 HO are collectively referred to as inter-gNB HO. According to 3GPP (registered trademark), inter-gNB HO is performed with priority over inter-AMF HO.
[0004] In a mobile communication network, the Network Functions (NFs) of the Core Network (CN) are usually deployed in a central site that is geographically different from the edge sites where the gNBs are installed. The NFs of the core network include, for example, the AMF that manages the mobility of the WDs, the Session Management Function (SMF) that manages PDU sessions for the WDs, and the User Plane Function (UPF) that processes data packets that the WDs transmit and receive on the PDU sessions. The AMF and SMF are NFs of the Control Plane (CP), and the UPF is an NF of the User Plane (UP). When these NFs are deployed in the central site, the WDs need to transmit and receive control signaling to and from the AMF and SMF deployed in the central site.
[0005] Non-Patent Document 1 discloses a configuration in which some NFs of CN, such as AMF and SMF, are placed at the same edge site as gNB. In the configuration of Non-Patent Document 1, the propagation delay of control signaling transmitted and received by WD is shortened, so that the control delay for WD can be shortened. [Prior art documents] [Non-patent literature]
[0006] [Non-Patent Document 1] Corici, Marius, Pousali Chakraborty, and Thomas Magedanz., "A Study of 5G Edge-Central Core Network Split Options", Network 1.3 (2021): 354-368. Summary of the Invention [Problem to be solved by the invention]
[0007] For example, as shown in Figure 2, AMF#1 and gNB#1 are provided at an edge site in area #1, and AMF#2 and gNB#2 are provided at an edge site in area #2. Also, as shown in Figure 2, AMF#1 and AMF#2 are connected via the N14 interface, AMF#1 is connected to gNB#1 and gNB#2 via the N2#11 interface and N2#12 interface, and AMF#2 is connected to gNB#1 and gNB#2 via the N2#21 interface and N2#22 interface. Note that in Figure 2, gNB#1 and gNB#2 are not connected via the Xn interface, but gNB#1 and gNB#2 may be connected to each other via the Xn interface.
[0008] As shown by the solid line in Figure 2, the WD is connected to gNB#1 and establishes a control plane session with AMF#1 via gNB#1. Here, as the WD moves, it is assumed that it is HO'd to gNB#2 as shown in Figure 3. In this case, inter-gNB HO is performed instead of inter-AMF HO according to the priority of the HO type. Because inter-gNB HO is performed, the WD establishes a control plane session with AMF#1 via gNB#2. In this way, even though AMF#2 is deployed at the edge site of area#2, the WD will send and receive control signaling with AMF#1 deployed at an edge site in another area, and the WD may not be able to enjoy the benefit of sending and receiving control signaling with AMF with low latency.
[0009] The present disclosure provides a technique for appropriately controlling the HO type applied to a WD. [Means for solving the problem]
[0010] According to one embodiment of the present disclosure, a network node of a mobile communication network comprises an acquisition means for acquiring a first condition requested by a wireless device (WD) that has established a control session with a first network node via a first base station from the WD, and a determination means for determining a handover type to be applied to the WD when the WD is handed over from the first base station to a second base station.When the WD is handed over from the first base station to the second base station, if a first handover type in which the WD establishes a control session with the first network node after the handover and a second handover type in which the WD establishes a control session with a second network node after the handover can be applied to the WD, the determination means determines the handover type to be applied to the WD based on whether a control packet transmitted and received between the first network node and the second base station satisfies the first condition and whether a control packet transmitted and received between the second network node and the second base station satisfies the first condition. [Effects of the Invention]
[0011] According to the present disclosure, the HO type applied to the WD can be appropriately controlled. [Brief explanation of the drawings]
[0012] [Figure 1] FIG. 10 is an explanatory diagram of handover types. [Figure 2] FIG. 10 is a diagram showing an example of handover when AMF is placed at an edge site. [Figure 3] FIG. 10 is a diagram showing an example of handover when AMF is placed at an edge site. [Figure 4] 1 is a diagram illustrating the configuration of a mobile communication network according to an embodiment. [Figure 5] FIG. [Figure 6] FIG. 10 is a diagram showing an example of determining the HO type applied to WD. [Figure 7] FIG. 2 illustrates an example configuration of a controller according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION
[0013] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Furthermore, the same reference numerals are used for the same or similar components, and redundant explanations will be omitted.
[0014] FIG. 4 is a configuration diagram of a mobile communication network according to this embodiment. Area #1 includes one or more edge sites. At least one gNB #1 is provided in each of the one or more edge sites in area #1. Furthermore, an AMF #1 is provided in at least one of the one or more edge sites in area #1. Furthermore, a controller #1 is provided in at least one of the one or more edge sites in area #1. Area #2 includes one or more edge sites. At least one gNB #2 is provided in each of the one or more edge sites in area #2. Furthermore, an AMF #2 is provided in at least one of the one or more edge sites in area #2. Furthermore, a controller #2 is provided in at least one of the one or more edge sites in area #2.
[0015] In Figure 4, only one gNB#1, one AMF#1, and one controller#1 provided in area #1 are shown, and only one gNB#2, one AMF#2, and one controller#2 provided in area #2 are shown, but the number of AMFs, gNBs, and controllers provided in each area may be multiple. In Figure 4, AMF#1 and AMF#2 are connected via the N14 interface. Also, AMF#1 is connected to gNB#1 and gNB#2 via the N2#11 interface and the N2#12 interface. Furthermore, AMF#2 is connected to gNB#1 and gNB#2 via the N2#21 interface and the N2#22 interface. Note that in Figure 4, gNB#1 and gNB#2 are not connected via the Xn interface, but gNB#1 and gNB#2 may be connected to each other via the Xn interface.
[0016] Controllers #1 and #2 are one of the NFs. Note that controllers #1 and #2 may be implemented in the same network node as another NF, for example, an AMF. Furthermore, the functions of controllers #1 and #2 described in the following description may be implemented as functions of another type of NF, such as an AMF. Controller #1 may be configured to be able to communicate with AMF #1 and gNB #1 provided in area #1 via a control interface. Similarly, controller #2 may be configured to be able to communicate with AMF #2 and gNB #2 provided in area #2 via a control interface. Furthermore, controller #1 and controller #2 are configured to be able to communicate with each other via a control interface.
[0017] In FIG. 4, the WD establishes a control session with AMF#1 via gNB#1. FIG. 5 is a sequence diagram according to this embodiment. In S10, the WD transmits a control condition registration request to the controller #1 via AMF#1 with which the control session is established. The control conditions may include a delay condition indicating the allowable amount of delay for a control packet carrying control signaling, and a jitter condition indicating the allowable amount of fluctuation in the control packet. Note that the control condition may be only a delay condition. Alternatively, the control condition may be only a jitter condition. Furthermore, the control condition may include other conditions in addition to the delay condition or the jitter condition. The controller #1 stores the control conditions of the WD.
[0018] In S11, controller #1 acquires a predicted result of handover for WD. For example, a network data analysis function (NWDAF) is provided in the mobile communication network. The NWDAF can estimate the movement state of the WD based on information collected from each NF in the mobile communication network, estimate the timing of handover to the WD based on the movement state, and estimate the target base station for handover. For example, controller #1 can acquire the timing of handover to the WD and the target base station for the handover (base station after handover) from the NWDAF in S11. Here, it is assumed that controller #1 acquires a predicted result from the NWDAF that WD will be handed over from gNB #1 to gNB #2.
[0019] Based on the prediction result obtained in S11, in S12, controller #1 obtains from AMF #1 information regarding the transmission status of control packets at the N2#12 interface. Specifically, controller #1 obtains the delay amount of control packets between AMF #1 and gNB #2 and the amount of jitter occurring in the transmission and reception of control packets between AMF #1 and gNB #2. Note that the delay amount and jitter amount may be maximum values, minimum values, or statistical values over a predetermined period of time in the past, for example, average values. When inter-gNB HO is applied to WD, the N2#12 interface is the N2 interface through which a control session for WD is established after HO.
[0020] Furthermore, based on the prediction result obtained in S11, controller #1 obtains information on the transmission status of control packets at the N2#22 interface from controller #2 in S13. Specifically, controller #1 obtains the amount of delay of control packets between AMF#2 and gNB#2 and the amount of jitter occurring in the transmission and reception of control packets between AMF#2 and gNB#2. Controller #2 obtains the status of the N2#22 interface from AMF#2. When inter-AMF HO is applied to WD, the N2#22 interface is the N2 interface where a control session for WD is established after HO.
[0021] In S14, when a WD is HO'd to gNB #2, controller #1 determines whether to apply inter-AMF HO or inter-gNB HO to the WD. FIG. 6 is an explanatory diagram of the processing in S14. Controller #1 determines whether the transmission and reception of control packets at the N2#12 interface satisfies the control conditions of WD based on the information acquired in S12. In this embodiment, the control conditions of WD include delay conditions and jitter conditions. Therefore, if the delay and jitter amounts of control packets transmitted and received at the N2#12 interface are equal to or less than the allowable delay and jitter amounts indicated in the control conditions of WD, the control conditions of WD are satisfied. Similarly, controller #1 determines whether the delay and jitter amounts of control packets transmitted and received at the N2#22 interface satisfy the control conditions of WD based on the information acquired in S13. In FIG. 6, ◯ indicates that the control conditions of WD are satisfied, and × indicates that the control conditions of WD are not satisfied.
[0022] If both the N2#12 interface and the N2#22 interface satisfy the control conditions for WD, the controller #1 determines that inter-gNB HO is the HO type to apply to WD according to the priority of the HO type. Also, if the N2#12 interface satisfies the control conditions for WD but the N2#22 interface does not, the controller #1 determines that inter-gNB HO that satisfies the control conditions is the HO type to apply to WD. Similarly, if the N2#22 interface satisfies the control conditions for WD but the N2#12 interface does not satisfy the control conditions for WD, the controller #1 determines that inter-AMF HO that satisfies the control conditions is the HO type to apply to WD.
[0023] In addition, if neither interface satisfies the WD control conditions, controller #1 selects inter-AMF HO or inter-gNB HO in any manner. For example, controller #1 can select inter-AMF HO if the delay amount of control packets at the N2#22 interface is smaller than the delay amount of control packets at the N2#12 interface, and can select inter-gNB HO if the delay amount of control packets at the N2#12 interface is smaller than the delay amount of control packets at the N2#22 interface. Also, for example, controller #1 can select inter-AMF HO if the jitter amount of control packets at the N2#22 interface is smaller than the jitter amount of control packets at the N2#12 interface, and can select inter-gNB HO if the jitter amount of control packets at the N2#12 interface is smaller than the delay amount of control packets at the N2#22 interface.
[0024] In S15 and S16, controller #1 notifies AMF #1 and gNB #1 of the HO type determined in S14. Note that, since the default priority of inter-gNB HO is higher than the default priority of inter-AMF HO, if it is determined that inter-gNB HO is applied to WD, the processes of S15 and S16 can be omitted. Thereafter, when WD moves into the cell of gNB #2, WD is handed over to gNB #2 according to the HO type determined by controller #1. Note that, for example, if inter-AMF HO is applied and WD establishes a control plane session with AMF #2 within the management range of controller #2, WD registers control conditions with controller #2 via AMF #2.
[0025] The above configuration can prevent the execution of an HO that does not satisfy the control conditions required by the WD, even if there is an HO type that satisfies the control conditions required by the WD. In other words, the HO type applied to the WD can be appropriately controlled.
[0026] Note that, since what is acquired in S11 is the predicted result of HO for the WD, multiple gNBs may be notified to controller #1 as HO targets depending on the movement state of the WD. In this case, controller #1 determines the HO type to apply to the WD for each of the notified multiple gNBs, and notifies AMF#1 and gNB#1 of the HO type to be applied for each HO target gNB. Also, in S13, controller #1 acquired information about the transmission status at the N2#22 interface from controller #2. This was because AMF#2 was within the management range of controller #2 in FIG. 4. However, if AMF#2 was within the management range of controller #1, not controller #2, in S13, controller #1 acquired information about the transmission status at the N2#22 interface from AMF#2.
[0027] In this embodiment, the AMF is configured to measure the transmission status of control packets in the N2 interface, i.e., the amount of delay and jitter of the control packets. However, the gNB may measure the transmission status of control packets in the N2 interface and notify the AMF. Furthermore, the gNB may be configured to provide an NF that monitors and measures control packets transmitted and received through the N2 interface. In this case, the controller acquires information on the transmission status of control packets in the N2 interface from the NF in S12. In this embodiment, the controller #1 notifies both the gNB #1 and the AMF #1 of the HO type in S15 and S16. However, the controller #1 may be configured to notify only the AMF #1 of the HO type in S15, and the AMF #1 may notify the gNB #1 of the HO type. In this case, the controller #1 does not need to be provided with a function for communicating with the gNB #1.
[0028] Furthermore, in the configuration of Fig. 4, both inter-gNB HO and inter-AMF HO are applicable to a WD handed over from gNB #1 to gNB #2. However, naturally, inter-gNB HO is applied when only inter-gNB HO is applicable, and inter-AMF HO is applied when only inter-AMF HO is applicable. In other words, the contents described in this embodiment are executed when both inter-gNB HO and inter-AMF HO are applicable to a WD.
[0029] <Device configuration> FIG. 7 shows a configuration example of the above-mentioned controller #1 and controller #2 (collectively referred to as controllers). The controller includes, for example, one or more processors and one or more memory devices. The one or more memory devices may include volatile memory devices and non-volatile memory devices. Each functional block shown in FIG. 7 may be realized by one or more processors executing a computer program stored in one or more memory devices. The controller may also be realized by a single device. Alternatively, the controller may be realized by multiple devices capable of communicating with each other. The controller is a network node of a mobile communication network. The controller may be implemented in the same network node as other NFs. For example, the controller may be implemented in the same network node as an AMF. Note that FIG. 7 shows only functional blocks necessary for understanding the present disclosure, and the controller may have functional blocks other than those shown in FIG. 7.
[0030] The acquisition unit 10 acquires and stores the control conditions of the WD via the AMF. Furthermore, the acquisition unit 10 acquires the base station to be the HO destination and the predicted timing for the WD for which the control conditions are stored from another NF, for example, the NWDAF. For example, when the determination unit 11 acquires the predicted result that a HO with a second base station as the HO destination will occur for a WD connected to a first base station, the determination unit 11 determines the HO type to apply to the WD in the HO. The determination method by the determination unit 11 may be, for example, the method described using FIG. 6. The notification unit 12 notifies the AMF and the base station so that the HO is performed according to the determination result by the determination unit 11.
[0031] The present disclosure also provides a computer program that, when executed by one or more processors in an apparatus having one or more processors, causes the apparatus to function as the controller described above, and a computer-readable storage medium storing the computer program. The present disclosure also provides a method executed by a controller for the process shown in Fig. 5, a computer program that causes an apparatus having one or more processors to execute the method, and a computer-readable storage medium storing the computer program.
[0032] As described above, it is possible to appropriately control the HO type applied to WD, which will contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is to "Build resilient infrastructure, promote sustainable industrialization, and foster innovation."
[0033] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention. [Explanation of symbols]
[0034] 10: Acquisition section, 11: Judgment section, 12: Notification section
Claims
1. A network node of a mobile communication network, comprising: an acquisition means for acquiring a first condition requested by a wireless device (WD) that has established a control session with a first network node via a first base station; a determination means for determining a handover type to be applied to the WD when the WD is handed over from the first base station to the second base station; Equipped with The determination means determines the handover type to be applied to the WD based on whether or not a control packet transmitted and received between the first network node and the second base station satisfies the first condition and whether or not a control packet transmitted and received between the second network node and the second base station satisfies the first condition when a first handover type in which the WD establishes a control session with the first network node after the handover and a second handover type in which the WD establishes a control session with a second network node after the handover can be applied to the WD when the WD is handed over from the first base station to the second base station.
2. 2. The network node according to claim 1, wherein the determination means determines to apply the first handover type to the WD when a control packet transmitted and received between the first network node and the second base station satisfies the first condition and a control packet transmitted and received between the second network node and the second base station satisfies the first condition.
3. 2. The network node according to claim 1, wherein the determination means determines to apply the second handover type to the WD when a control packet transmitted and received between the first network node and the second base station does not satisfy the first condition and a control packet transmitted and received between the second network node and the second base station satisfies the first condition.
4. 2. The network node according to claim 1, wherein the determination means determines to apply the first handover type to the WD when a control packet transmitted and received between the first network node and the second base station satisfies the first condition and a control packet transmitted and received between the second network node and the second base station does not satisfy the first condition.
5. 2. The network node according to claim 1, wherein the determination means determines to apply either the first handover type or the second handover type to the WD when a control packet transmitted and received between the first network node and the second base station does not satisfy the first condition and when a control packet transmitted and received between the second network node and the second base station does not satisfy the first condition.
6. the first condition includes a delay condition; 6. The network node according to claim 5, wherein, when a control packet transmitted and received between the first network node and the second base station does not satisfy the first condition and a control packet transmitted and received between the second network node and the second base station does not satisfy the first condition, the determination means determines to apply the first handover type to the WD if a delay amount of the control packet transmitted and received between the first network node and the second base station is smaller than a delay amount of the control packet transmitted and received between the second network node and the second base station, and determines to apply the second handover type to the WD if a delay amount of the control packet transmitted and received between the first network node and the second base station is larger than a delay amount of the control packet transmitted and received between the second network node and the second base station.
7. the first condition includes a jitter condition; 6. The network node according to claim 5, wherein, when a control packet transmitted and received between the first network node and the second base station does not satisfy the first condition and a control packet transmitted and received between the second network node and the second base station does not satisfy the first condition, the determination means determines to apply the first handover type to the WD if an amount of jitter in the control packet transmitted and received between the first network node and the second base station is smaller than an amount of jitter in the control packet transmitted and received between the second network node and the second base station, and determines to apply the second handover type to the WD if an amount of jitter in the control packet transmitted and received between the first network node and the second base station is larger than an amount of jitter in the control packet transmitted and received between the second network node and the second base station.
8. 2. The network node according to claim 1, wherein the determination means determines whether a control packet transmitted and received between the first network node and the second base station satisfies the first condition based on a transmission state of the control packet transmitted and received between the first network node and the second base station, obtained from the first network node.
9. 2. The network node according to claim 1, wherein the determination means determines whether a control packet transmitted and received between the second network node and the second base station satisfies the first condition based on a transmission state of the control packet transmitted and received between the second network node and the second base station, acquired from the second network node or another network node.
10. The network node according to claim 1 , wherein the first network node and the second network node are nodes implementing access and mobility management functions.
11. The network node of claim 1 , wherein the first network node and the network node are implemented in the same device.
12. A computer program that, when executed on one or more processors of an apparatus having one or more processors, causes the apparatus to function as a network node according to any one of claims 1 to 11.