IP Address Assignment in a Wireless Communication Network

Abstract

To provide the invention related to a user plain (UP) core network function in a radio communication network, and provide a method for reducing a possibility of failure when performing a request for allocating an internet protocol (IP) address to user equipment (UE) to an UP function.SOLUTION: A method contains steps of: managing an IP address by an UP function to set an allocation for an UE; transmitting a request message (e.g., a PFCP session establishment request) to the UP function by a CP function; requesting an allocation of the IP address to the UE associated with a session that has to be established by the UP function; and transmitting a response message such as a PFCP session establishment response containing an instruction of the IP address to allocate a UE IP address and to be allocated by the UP function to the CP function.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to communications, and more particularly, to methods and apparatuses related to IP address allocation in a wireless communication network.

Background Art

[0002] This section introduces aspects that may facilitate a better understanding of the present disclosure. Accordingly, the description of this section should be read in this regard and should not be construed as an admission as to what is in the prior art or what is not in the prior art.

[0003] When a user equipment (UE) connects to a wireless communication network, an Internet Protocol (IP) address is assigned to the UE by the core network to enable easy data connectivity between the UE and a packet data network (PDN). Prior to Release 16 of the 3rd Generation Partnership Project (3GPP), the IP address was assigned to the UE by a control plane function within the core network, such as a PDN gateway (PGW-C) in the control plane. In Release 16 of the 3GPP specifications, the assignment of the UE IP address by a user plane (UP) function was introduced.

[0004] Accordingly, the UP function can manage and assign a UE IP address for each PDN or protocol data unit (PDU) session. The UP function receives a request to establish a session, such as a packet forwarding control protocol (PFCP) session establishment request, from a control plane (CP) function, assigns a UE IP address, and sends that UE IP address in a PFCP session establishment response to the CP function. The CP function can be, for example, a PDN gateway (PGW-C) in the control plane or a session management function (SMF).

[0005] 3GPP Technical Specification (TS) 29.244, v16.3.1 presents the details regarding this process as follows (see section 5.21.3).

[0006] When performing UE IP address / prefix allocation in the UP function, the CP function shall request the UP function to allocate a UE IP address / prefix by doing the following. - Set the CHOOSE flag (CHOOSE IPV4 and / or CHOOSE IPV6) in the UE IP address information element (IE) of the Packet Detection Rule (PDR: see Table 7.5.2.2-1) or Traffic Endpoint (see Table 7.5.2.7-1), where an IPv6 prefix other than the default value / 64 and other than for IPv6 prefix delegation (see section 5.14) should be allocated, and where the User Plane Function (UPF) has indicated support for the IP6PL feature (see section 8.2.25), the IPv6 prefix length shall be indicated in the UE IP address, and - Include a Network Instance IE for indicating the IP address pool from which the UE IP address / prefix should be allocated. - Optionally, include UE IP address pool identification information, assuming the UE IP address is to be allocated from it by the UP function.

[0007] The CP function may request the UP function to allocate the same UE IP address / prefix to several PDRs to be created within one single PFCP session establishment request or PFCP session modification request by doing the following. - Set the CHOOSE flag (CHOOSE IPV4 and / or CHOOSE IPV6) in the UE IP address IE of each PDR to be created with the new UE IP address / prefix, Alternatively, if the UP function indicates support for packet detection information (PDI) optimization (see section 8.2.25), - By including only the UE IP address IE in the traffic endpoint creation IE, and setting the CHOOSE flag (CHOOSE IPV4 and / or CHOOSE IPV6) in the UE IP address IE of this IE, and - By including the traffic endpoint ID in all PDRs that should be created with the same UE IP address. If one or more PDRs are successfully created, the UP function shall return in the PFCP session establishment response or PFCP session modification response the UE IP address / prefix that the UP function has allocated to the one or more PDRs or to the one or more traffic endpoints. Upon receiving a request to delete the PFCP session, remove the traffic endpoint, or remove the last PDR associated with the UE IP address / prefix, the UP function shall release the UE IP address / prefix allocated to the PFCP session, the traffic endpoint, or the PDR.

[0008] Accordingly, embodiments of the present disclosure may be implemented in a fifth generation (5G) core network. FIG. 1 shows an architecture for a 5G system. As shown, the 5G system includes a user equipment (UE), a (radio) access network ((R)AN), a user plane function (UPF), a data network (DN), an authentication server function (AUSF), an access and mobility management function (AMF), a session management function (SMF), a service communication proxy (SCP), a network slice selection function (NSSF), a network exposure function (NEF), a network repository function (NRF), a policy control function (PCF), an integrated data management (UDM), and an application function (AF).

[0009] The 5G architecture is defined as service-based, and the interactions between network functions (NFs) are represented in two ways. One way is the service-based representation, where an NF (e.g., AMF) in the control plane enables other permitted NFs to access its services. This representation also includes point-to-point reference points if necessary. The other way is the reference point representation, which indicates the interactions that exist between NF services in an NF, described by the point-to-point reference points (e.g., N11) between any two NFs (e.g., between AMF and SMF).

[0010] The NEF supports the external disclosure of the capabilities of the NF. The external disclosure can be categorized as monitoring capabilities, provisioning capabilities, policy / billing capabilities, and analysis reporting capabilities. The monitoring capabilities are for monitoring specific events regarding UEs in the 5G system and making such monitoring event information available for external disclosure via the NEF. The provisioning capabilities are for enabling external parties to provision information that can be used for UEs in the 5G system. The policy / billing capabilities are for handling the quality of service (QoS) and billing policies for UEs based on requests from external parties. The analysis reporting capabilities are for enabling external parties to fetch or subscribe to the analysis information generated by the 5G system / unsubscribe from such information.

Summary of the Invention

[0011] The summary of the present invention is provided to introduce, in a simplified form, a selection of concepts that will be further described below in the detailed description of the embodiments for carrying out the invention. The summary of the present invention does not identify the main features or essential features of the claimed subject matter, nor is it used to limit the scope of the claimed subject matter.

[0012] One of the objectives of the present disclosure is to reduce network resource waste and latency due to failed requests for UE IP address allocation by the UP function.

[0013] According to a first aspect of the present disclosure, a method implemented by a user plane core network function for a wireless communication network is provided. A range of IP addresses for allocation to UEs is set in the user plane core network function. The method includes sending a message to a control plane core network function. The message includes an indication of the usage level of the range of IP addresses.

[0014] According to a second aspect of the present disclosure, a method implemented by a control plane core network function for a wireless communication network is provided. The method includes receiving a message from one or more user plane core network functions. Each range of IP addresses for assignment to a UE is set in the user plane core network function. At least one of the messages includes an indication of the usage level of the range of IP addresses. The method further includes selecting a user plane core network function to assign an IP address to the UE based on the indicated usage level.

[0015] Embodiments of the present disclosure have the technical advantage of reducing the possibility of failure when requesting a UP function to assign an IP address to a UE. In this way, the delay in establishing a PDU / PDN session for the UE is reduced, and network resources are utilized more efficiently.

[0016] These and other objects, features, and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure, which should be read in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0017]

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DETAILED DESCRIPTION OF THE INVENTION

[0018] For the purpose of explanation, in the following description, details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent to those skilled in the art that the embodiments may be practiced without these specific details or with equivalent configurations.

[0019] One problem identified by the inventors relates to UE IP address allocation by UP core network functions such as 3GPP-specified User Plane Functions (UPF) and PGW-U. The UP functions configured to provide this functionality have a finite range of IP addresses for dynamic allocation to UEs. However, the CP functions that request UE IP address allocation may not know whether that range is fully or almost fully used in the UP functions, and the CP functions may still select a UP function to allocate an IP address to a UE. If all dynamic IP addresses are occupied (e.g., already allocated to other UEs), or if all dynamic IP addresses in the UE IP address pool indicated by the CP function are occupied, the UP function will reject the PFCP session establishment request. Thus, the allocation of IP addresses to UEs is delayed and network resources are wasted (e.g., used in failed requests for IP address allocation). Even after such failed requests, the CP functions may continue to select a UP function for UE IP address allocation because the request may have been rejected for reasons other than all dynamic IP addresses being occupied.

[0020] This disclosure proposes an improved solution for UE IP address allocation by UP core network functions. As an exemplary example, the solution may be applied to the communication system shown in FIG. 1. The functional description of the entities shown in FIG. 1 is specified in section 6 of 3GPP TS23.501, v16.4.0, which is hereby incorporated by reference in its entirety. Alternatively, embodiments may be implemented in other networks that include a separation between the user plane and the control plane and where the user plane is utilized to allocate IP addresses for wireless devices.

[0021] In the context of the present disclosure, it should be noted that the term terminal device (or UE) as used herein may also be referred to as, for example, an access terminal, a mobile station, a mobile unit, a subscriber station, etc. The term terminal device (or UE) may refer to any (fixed or mobile) end device that can access a wireless communication network and receive services from the wireless communication network. By way of non-limiting example, a UE may include a portable computer, an image capture terminal device such as a digital camera, a gaming terminal device, a music storage and playback device, a mobile phone, a cellular phone, a smartphone, a tablet, a wearable device, a personal digital assistant (PDA), an integrated or embedded wireless card, an external plug-in wireless card, etc.

[0022] In the Internet of Things (IoT) scenario, the terminal device (or UE) may represent a machine or other device that performs monitoring and / or measurement and transmits the results of such monitoring and / or measurement to another terminal device (or UE) and / or network equipment. In this case, the terminal device (or UE) may be a machine-to-machine (M2M) device, and an M2M device may sometimes be referred to as a machine type communication (MTC) device in the 3GPP context. Specific examples of such machines or devices may include sensors, metering devices such as power meters, industrial machinery, motorcycles, vehicles, or household or personal electrical appliances, such as personal wearables like refrigerators, televisions, watches, etc.

[0023] As used herein, the term "communication system" refers to a system that complies with any suitable communication standard, such as the 1st generation (1G) communication protocol, 2G communication protocol, 2.5G communication protocol, 2.75G communication protocol, 3G communication protocol, 4G communication protocol, 4.5G communication protocol, 5G communication protocol, and / or any other protocol that is currently known or will be developed in the future. Further, the communication between the terminal device and the network node (or network entity) in the communication system can be carried out according to any suitable generation of communication protocol, including but not limited to the 1G communication protocol, 2G communication protocol, 2.5G communication protocol, 2.75G communication protocol, 3G communication protocol, 4G communication protocol, 4.5G communication protocol, 5G communication protocol, and / or any other protocol that is currently known or will be developed in the future. Further, the specific terms used herein do not limit the present disclosure to only the communication systems related to the specific terms, which can be generally applied by other communication systems.

[0024] As used herein, the term "UP core network function" refers to the core network function in the user plane, and includes, for example, UPF and PGW-U. The term "UP function" is also used for this purpose. The acronym "UPF" explicitly refers to the core network function defined in the 3GPP specification as a user plane function, for example, in 3GPP TS23.501, v16.4.0, section 6.2.3. The terms "CP function" and "CP core network function" are synonymous and refer to the core network functions in the control plane, such as PGW-C and SMF.

[0025] Therefore, as described above, a range of IP addresses for allocation to UEs can be set for the UP function in a wireless communication network, such as that shown in FIG. 1. When receiving a request message from the CP function, the UP function allocates an available IP address from the range of the UP function's IP addresses and sends a response message including an indication of the allocated IP address. However, the range of IP addresses may be exhausted so that the UP function can no longer allocate IP addresses to UEs.

[0026] According to an embodiment of the present disclosure, the UP function is set to send a message including an indication of the usage level of the range of the UP function's IP addresses to the CP function. In this way, the CP function is notified of the usage level in the UP function and can take this into account when selecting the UP function to request the allocation of IP addresses to UEs in the future. For example, the CP function may select not to select (or select with a lower frequency or probability) a UP function that reports a high usage level or absence of available IP addresses.

[0027] The indication of the usage level may include an indication of the ratio of the range of IP addresses that are currently allocated, such as a percentage. The indication of the ratio may be implicit or explicit. In the former case, for example, the indication may be of the ratio of the range of IP addresses that are currently available. Since the IP addresses can be either allocated or available, the former ratio indication is an implicit indication of the latter ratio, and vice versa.

[0028] The indication of the usage level may include, additionally or alternatively, the absolute number of available IP addresses in the range. Similarly, the indication of the absolute number may be implicit or explicit. In the former case, for example, the indication may include an indication of the total number of IP addresses in the range (both available and allocated) and the number of allocated IP addresses. Therefore, the number of available IP addresses can be derived by subtraction from these amounts.

[0029] The message may include a response message to a request from the CP function regarding the assignment of an IP address to the UE. Examples of this embodiment are shown below in FIGS. 2 and 3. An indication of the usage level may be included in such a message, for example, in response to the usage level exceeding a threshold. In this way, network resources are not utilized to report the usage level until and unless the usage level reaches a value at which there is a possibility that the request to assign an IP address to the UE may be rejected due to all IP addresses being assigned. Alternatively, the message may be autonomously transmitted by the UP function, for example, in response to a subscription request from the CP function. In this case, the message may be transmitted, for example, in response to the usage level exceeding a threshold. Examples of this embodiment are shown below in FIGS. 4 and 5.

[0030] The range of IP addresses set in the UP function may include one or more UE IP address pools. Each of the UE IP address pools may be associated with a specific network instance set in the UP function. That is, each network instance of the UP function may be associated with one or more UE IP address pools.

[0031] An IP address may be assigned to the UE for each PDN or PDU session, for example, at the establishment of such a session. Thus, the UE may have multiple IP addresses if the UE has multiple PDNs or PDU sessions.

[0032] Additionally or alternatively, some embodiments provide a mechanism by which the UP function can report that the failure to assign an IP address to the UE has been caused by the range of IP addresses in the UP function being exhausted.

[0033] Figure 2 is a signaling diagram showing signaling according to an embodiment of the present disclosure between a CP function and a UP function. The CP function may correspond to, for example, a PGW-C or an SMF. The UP function may correspond to, for example, a PGW-U or a UPF. In one embodiment, when the CP function corresponds to a PGW-C and the UP function corresponds to a PGW-U, transmission between network functions is performed via the Sxb interface. In another embodiment, when the CP function corresponds to an SMF and the UP function corresponds to a UPF, transmission between network functions is performed via the N4 interface. In a further embodiment, different UP functions and CP functions may be utilized and messages may be transmitted on different interfaces (such as the Sxa and Sxc interfaces).

[0034] In step 1, the UP function is configured to manage and allocate IP addresses to UEs, for example, as described above.

[0035] In step 2, the CP function sends a request message (such as a PFCP session establishment request) to the UP function, requesting that the UP function allocate an IP address to the UE associated with the session to be established. According to 3GPP TS29.244, v16.3.1, the request to allocate an IP address may be indicated by Create PDR / PDI / UE IP address / CHOOSE, where a CHOOSE value of 1 indicates that the CP function requires the UP function to allocate a UE IP address for this PDN / PDU session.

[0036] In step 3, the UP function allocates a UE IP address and sends a response message (such as a PFCP session establishment response) containing an indication of the allocated IP address to the CP function. The allocated UE IP address may be associated with one or more PDRs. Further, according to an embodiment of the present disclosure, the response message includes a new IE, i.e., UE IP address allocation information. The IE includes an indication of the usage level of the range of IP addresses set in the UP function. In the illustrated example, this includes an indication of the ratio (e.g., percentage) of the allocated IP address range (UE IP address allocation metric: 56%) and an indication of the absolute number of IP addresses that are available, i.e., not allocated (number of UE IP addresses: 100K). Further, the IE includes a sequence number associated with the information element (UE IP address sequence number: 1), which enables the CP function to determine the current usage level in the UP function by using the usage level with the most recent (e.g., highest) sequence number, rather than the previously indicated usage level. In some embodiments, this sequence number is incremented by each indication of the usage level (e.g., each transmission of the UE IP address allocation information IE), or alternatively, the sequence number may be incremented each time the usage level changes. Table 1 below shows a list of information elements that may be included in the message sent in step 3. The list includes a new IE, i.e., UE IP address allocation information, including an indication of the usage level, according to an embodiment of the present disclosure.

[0037] In step 4, the range of IP addresses in the UP function is almost exhausted.

[0038] In step 5, for another new PDU / PDN session, the CP function sends a request message (e.g., a PFCP session establishment request with CREATE PDR / PDI / UE IP address / CHOOSE) instructing the UP function to allocate a UE IP address for this PDN / PDU session again.

[0039] In step 6, similar to step 3 above, the UP function again assigns a UE IP address and sends a response message with an indication of the assigned IP address (e.g., the PDR / UE IP address created in the PFCP session establishment response) to the CP function. Similarly, as in step 3, this message includes a new IE that indicates the usage level of the IP address range. In this message, the sequence number is incremented (i.e., UE IP address sequence number: 2), and the usage level indication indicates a higher ratio of the assigned address (UE IP address allocation metric: 96%) and fewer available IP addresses (UE IP address: 0.5K).

[0040] Based on the indicated usage level, in step 7, the CP function adapts the algorithm used to select a UP function for assigning an IP address to the UE. For example, the algorithm can be adapted such that the UP function is less likely to be selected or is selected less frequently. In one embodiment, the algorithm can be adapted such that the UP function is not selected for assigning an IP address to the UE.

[0041] In step 9, the CP function sends a message related to the ongoing PDN / PDU session associated with the UP function. For example, the message can include a request to modify some aspect of the session, such as a PFCP session modification request.

[0042] In step 10, the UP function transmits a response message (e.g., PFCP session modification response) for the message sent in step 9 to the CP function. Before step 9, in step 8, the use of the IP address range in the UP function had returned to a lower value. For example, some of the assigned IP addresses may have had their associated PDN / PDU sessions terminated. Therefore, the response message sent in step 10 includes an indication of the new, lower usage level of the IP address range. In this message, the sequence number has been incremented again (i.e., UE IP address sequence number: 3), and the usage level indication shows a lower ratio of the assigned addresses (UE IP address allocation metric: 36%) and a larger number of available IP addresses (UE IP address: 900K). Table 2 below shows a list of information elements that may be included in the message sent in step 10. The list includes a new IE according to an embodiment of the present disclosure, namely, UE IP address allocation information, including the usage level indication.

[0043] Based on the indicated usage level, in step 11, the CP function adapts the algorithm used to select the UP function to assign an IP address to the UE again. For example, the algorithm may be adapted so that the UP function is more likely to be selected or is selected more frequently. In one embodiment, the algorithm may be adapted so that the CP function begins to select the UP function to assign an IP address to the UE again.

[0044] In step 12, the CP function selects the UP function to assign an IP address to the UE and, thus, sends a request message (e.g., PFCP session establishment request with create PDR / PDI / UE IP address / CHOOSE) to the UP function, similar to steps 2 and 5 above.

[0045] In step 13, the UP function assigns a UE IP address and sends a response message (e.g., a PFCP session establishment response with the assigned PDR / UE IP address) with an indication of the assigned IP address to the CP function. The response message includes an indication of the current usage level of the IP address range (UE IP address sequence number: 4, UE IP address assignment metric: 38%, number of UE IP addresses: 800K).

[0046] In one embodiment, the indication of the usage level of the IP address range in the UP function is included in the response message (e.g., those sent in steps 3, 6, 10, and 13) in response to the usage level exceeding a threshold. For example, the threshold can be set at a value relatively close to full utilization of the IP address range (e.g., 80% or 90%) in relation to the ratio of assigned IP addresses. Alternatively, the threshold can be set at a relatively low value (e.g., 1K) in relation to the number of available IP addresses. Thus, if the response message does not include an indication of the usage level, the CP function can assume that the usage level is not high, and the UP function can be selected for UE IP address assignment.

[0047] Although not shown in FIG. 2, it is possible that the entire range of IP addresses in the UP function is allocated, and thus, one of the request messages received in steps 2, 5, 9, and 12 may result in a failed allocation of an IP address to the UE. In this case, the response message transmitted in steps 3, 6, 10, and 13 may include an indication that the IP address allocation has failed instead of an indication of the IP address allocated to the UE. According to an embodiment of the present disclosure, the response message may further include an indication that the cause of the failure was the fully allocated range of IP addresses. Such an indication may be included within a cause IE, such as that shown in FIG. 12. The cause value indicates both whether the request to allocate an IP address to the UE was successful and the reason behind the rejection if the request was rejected. Table 8 below shows possible cause values that may be included in such a response message. It can be seen that an additional cause value (if the unallocated value xx is provided) is included to indicate that the request was rejected because all dynamic IP addresses were allocated.

[0048] FIG. 3 is a signaling diagram showing signaling according to a further embodiment of the present disclosure. This embodiment corresponds well to the embodiment shown in FIG. 2 and described above, with the difference that the indication of the usage level of the IP address range in the UP function is not presented in a dedicated IE, but instead is a sub-IE within another IE, such as a load control information IE. Table 3 below shows the load control information IE according to this embodiment. The IE includes a new sub-IE, namely UE IP address allocation information, which includes an indication of the usage level according to an embodiment of the present disclosure.

[0049] Figure 4 is a signaling diagram showing signaling according to a further embodiment of the present disclosure. In this embodiment, the indication of the usage level of the IP address range is transmitted autonomously by the UP function, that is, without responding to a message from the CP function. For example, the UP function may transmit such a message in response to the usage level exceeding a threshold or falling below a threshold.

[0050] Steps 1 to 4 are the same as steps 1 to 4 in FIGS. 2 and 3 above, except that the response message transmitted in step 3 does not include the indication of the usage level of the IP address range described above. The UP function is responsible for managing and allocating the UE IP address for each PDN / PDU session.

[0051] In step 5, the UP function sends a message including an indication of the usage level of the IP address range in the UP function to the CP function. The message can be a PFCP node report request or, as shown in FIG. 4, a PFCP association update request. The indication of the usage level may be included in a dedicated IE as described above. In the illustrated example, this includes an indication of the ratio (e.g., percentage) of the allocated IP address range (UE IP address allocation metric: 96%) and an indication of the absolute number of available, i.e., unallocated, IP addresses (number of UE IP addresses: 0.5K). Further, the IE includes a sequence number associated with the information element (UE IP address sequence number: 1), which enables the CP function to determine the current usage level in the UP function rather than the previously indicated usage level by using the usage level with the most recent (e.g., highest) sequence number. Table 4 below shows the IEs that may be included in the message transmitted in step 5 (and also in step 9 described below). The list includes new IEs including an indication of the usage level, i.e., UE IP address allocation information, according to an embodiment of the present disclosure.

[0052] In one embodiment, the message is sent in step 5 in response to the usage level exceeding a threshold. For example, the threshold can be related to the ratio of the assigned IP addresses and can be set at a value relatively close to full usage of the IP address range (e.g., 80% or 90%). Alternatively, the threshold can be related to the number of available IP addresses and can be set at a relatively low value (e.g., 1K).

[0053] In step 6, the CP function sends a response message, such as a PFCP node report response or, as shown in the figure, a PFCP association update response, to the UP function.

[0054] Steps 7 and 8 are the same as steps 7 and 8 described above with respect to FIGS. 2 and 3. Accordingly, the CP function adapts the algorithm used to select the UP function to assign an IP address to the UE. For example, the algorithm can be adapted so that the UP function is less likely to be selected or is selected less frequently. In one embodiment, the algorithm can be adapted so that the UP function is not selected to assign an IP address to the UE. At some later time, the usage level drops in step 8.

[0055] In step 9, the UP function sends a message (e.g., a PFCP node report request or a PFCP association update request) to the CP function. The message includes an indication of the new, lower usage level of the IP address range. In this message, the sequence number is incremented (i.e., UE IP address sequence number: 2), and the usage level indication shows a lower ratio of the assigned addresses (UE IP address assignment metric: 56%) and a larger number of available IP addresses (UE IP address: 100K).

[0056] In one embodiment, the message is sent in step 9 in response to the usage level falling below a threshold. For example, the threshold may be related to the ratio of assigned IP addresses or the number of available IP addresses. The threshold may be the same value as the threshold described above with respect to step 5, or a different value (e.g., a lower value) such that the message is not sent at an increased frequency when the usage level is at or near the threshold.

[0057] In step 10, the CP function sends a response message (e.g., a PFCP node report response or a PFCP association update response) to the UP function.

[0058] Steps 11 - 13 are the same as steps 11 - 13 described above with respect to FIGS. 2 and 3, except that the response message sent in step 13 does not include an indication of the usage level of the range of IP addresses in the UP function.

[0059] FIG. 5 is a signaling diagram showing signaling according to a further embodiment of the present disclosure. In this embodiment, an indication of the usage level of the range of IP addresses is sent by the UP function under the terms of a subscription by the CP function. Also, in this example, the UP function may send an indication of the usage level in response to the usage level exceeding or falling below a threshold.

[0060] In step 1, the CP function sends a subscription request message (e.g., PFCP association setup request) to the UP function such that the UP function reports the usage level within the range of the UP function's IP address. The subscription request message may include one or more conditions based on which the usage level should be reported. For example, the conditions may include a threshold usage level above which the usage level should be reported, a threshold usage level below which reporting of the usage level should stop, and / or how often the usage level should be reported. In one embodiment, the conditions may include multiple thresholds such that the UP function reports the usage level of the UP function when the usage level exceeds a specific threshold. Table 5 below shows the IEs that may be included in the messages sent in steps 7 and 11 of FIG. 5. The list includes a new IE, namely UE IP address allocation information, which includes a request for the UP function to report the usage level of the UP function and may also include an indication of one or more conditions.

[0061] In step 2, the UP function sends a response or acknowledgment message (e.g., PFCP association setup response) to the CP function. Thereafter, an indication of the usage level is sent by the UP function to the CP function under the conditions presented during the subscription. Steps 3 - 15 respectively correspond to steps 1 - 13, which were described above with respect to FIG. 4 in some cases.

[0062] Table 6 below shows the IEs that may be included in the messages sent in steps 7 and 11 of FIG. 5. The list includes new IEs, namely, UE IP address allocation information, including an indication of the usage level, according to an embodiment of the present disclosure. FIG. 11 shows the structure of the node report type IE listed in Table 6. It can be seen that bit 5 of octet 5 includes a bit for UE IP address allocation information (UIAAR), and this bit is set (e.g., to "1") to indicate the presence of the UE IP address allocation information IE in the message. The messages sent in steps 7 and 11 (e.g., PFCP node report requests) can be sent by the UP function on the Sxa, Sxb, Sxc, and N4 interfaces to report information not specific to the PFCP session to the CP function.

[0063] FIG. 6 is a flowchart showing a method implemented in the UP function according to an embodiment of the present disclosure. The flowchart may correspond to the signaling performed by the UP function in any of FIGS. 2 to 5 in some parts. The UP function may correspond to, for example, a UPF or a PGW-U. An IP address range for allocation to UEs is set in the UP function. The IP address range set in the UP function may include one or more UE IP address pools. Each of the UE IP address pools may be associated with a specific network instance set in the UP entity. That is, each network instance of the UP function may be associated with one or more UE IP address pools.

[0064] In block 600, the UP function receives a message from the CP function. The message may include a request for the UP function to assign an IP address to the UE, for example, as part of a request to establish a PDU or PDN session for the UE. See, for example, step 2 in FIGS. 2 and 3. In these examples, the request message may include an indication of the network instance of the UP function and may also include an identifier of a UE IP address pool from which the IP address is to be assigned by the UP function. Alternatively, the message may include a subscription request for the UP function to report its usage level. See, for example, step 1 in FIG. 5.

[0065] Block 602 presents an optional embodiment in which the UP function reports its usage level if the usage level exceeds a threshold. Thus, in block 602, the UP function determines whether the usage level of the configured range of the UP function of the IP address exceeds the threshold. For example, the threshold may be related to the ratio of the assigned IP addresses and may be set at a value relatively close to full utilization of the IP address range (e.g., 80% or 90%). Alternatively, the threshold may be related to the number of available IP addresses and may be set at a relatively low value (e.g., 1K). If the usage level does not exceed the threshold, the method ends and the UP function does not report its usage level to the CP function. For example, the UP function may not respond to the message received in step 600 (especially if the message was a subscription request) or may respond without an indication of the usage level of the UP function (especially if the message was a request for the UP function to assign an IP address to the UE). If the usage level exceeds the threshold, the method proceeds to step 604 and the UP function reports its usage level to the CP function. Alternatively, the UP function may not be configured in this manner and may proceed directly to step 604 after step 600.

[0066] In step 604, the UP function transmits a message including an indication of the usage level of the IP address range in the UP function to the CP function. The indication of the usage level may include an indication of the ratio of the IP address range, such as a percentage, that is currently allocated. The indication of the ratio may be implicit or explicit. In the former case, for example, the indication may be of the ratio of the IP address range that is currently available. Since the IP address may be either allocated or available, the former indication of the ratio is an implicit indication of the latter ratio, and vice versa. The indication of the usage level may include, additionally or alternatively, the absolute number of available IP addresses in the range. Similarly, the indication of the absolute number may be implicit or explicit. In the former case, for example, the indication may include an indication of the total number of IP addresses in the range (both available and allocated) and the number of allocated IP addresses. Thus, the number of available IP addresses may be derived by subtraction from these amounts.

[0067] According to some embodiments of the present disclosure, the message may include a sequence number associated with the indication of the usage level of the IP address range, which enables the CP function to determine the current usage level in the UP function by utilizing the usage level with the most recent (e.g., highest) sequence number, rather than the previously indicated usage level. In some embodiments, this sequence number is incremented by each indication of the usage level (e.g., each transmission of the UE IP address allocation information IE), or alternatively, the sequence number may be incremented each time the usage level changes.

[0068] The message transmitted in step 604 may include a response message to a request from the CP function regarding the allocation of an IP address to the UE. Examples of this embodiment were shown above in FIGS. 2 and 3 (see, for example, step 3 in those figures). An indication of the usage level may be included in such a message, for example, in response to the usage level exceeding a threshold. In this way, network resources are not utilized to report the usage level until and unless the usage level reaches a value at which there is a possibility that the request to allocate an IP address to the UE may be rejected due to all IP addresses being allocated. Alternatively, the message may be autonomously transmitted by the UP function, for example, in response to a subscription request from the CP function. In this case, the message may be transmitted, for example, in response to the usage level exceeding a threshold. Examples of this embodiment are shown below in FIGS. 4 and 5.

[0069] To represent usage levels for different UE IP address pools and / or different network instances, two or more indications of the usage level (for example, in the same type of IE) may be included.

[0070] According to some embodiments, if the message transmitted in step 604 includes a response to a request to allocate an IP address to the UE, and that request fails due to the fully allocated range of IP addresses in the UP function, the message may further include an indication that the failure to allocate an IP address to the UE was caused by the exhaustion of the range of IP addresses in the UP function. The indication may include a cause value corresponding to that meaning. See, for example, Table 8.

[0071] FIG. 7 is a flowchart showing a method implemented in a CP entity according to an embodiment of the present disclosure. The flowchart may correspond to signaling implemented by the UP function in any of FIGS. 2 to 5 in some parts. The CP entity may correspond to, for example, an SMF or a PGW-C.

[0072] In block 700, the CP function sends one or more messages to one or more UP functions. The UP function may correspond to, for example, a UPF or a PGW-U. A range of IP addresses for assignment to the UE is set in the UP function. The range of IP addresses set in the UP function may include one or more UE IP address pools. Each of the UE IP address pools may be associated with a specific network instance set in the UP entity. That is, each network instance of the UP function may be associated with one or more UE IP address pools.

[0073] The messages sent in block 700 may include, for example, a request for the UP function to assign IP addresses to those UEs when establishing a PDU / PDN session for the UE. See, for example, FIGS. 2 and 3. Alternatively or additionally, those messages may include a subscription request for the UP function to report the usage level of the UP function. See, for example, FIG. 5. The subscription request message may include one or more conditions based on which the usage level should be reported. For example, the conditions may include a threshold usage level above which the usage level should be reported, a threshold usage level below which reporting of the usage level should be stopped, and / or how often the usage level should be reported. In one embodiment, the conditions may include a plurality of thresholds such that the UP function reports the usage level of the UP function when the usage level exceeds a specific threshold.

[0074] In block 702, the CP function receives one or more messages from one or more UP functions. At least one of the messages includes an indication of the usage level of the range of IP addresses in each UP function. The indication of the usage level may include an indication of the ratio of the range of IP addresses that are currently allocated, such as a percentage. The indication of the ratio may be implicit or explicit. In the former case, for example, the indication may be of the ratio of the range of IP addresses that are currently available. Since the IP addresses can be either allocated or available, the former indication of the ratio is an implicit indication of the latter ratio, and vice versa. The indication of the usage level may alternatively or additionally include the absolute number of available IP addresses in the range. Similarly, the indication of the absolute number may be implicit or explicit. In the former case, for example, the indication may include an indication of the total number of IP addresses in the range (both available and allocated) and the number of allocated IP addresses. Thus, the number of available IP addresses can be derived by subtraction from these amounts.

[0075] According to some embodiments of the present disclosure, the message may include a sequence number associated with the indication of the usage level of the range of IP addresses, which enables the CP function to determine the current usage level in the UP function by utilizing the usage level with the most recent (e.g., highest) sequence number, rather than the previously indicated usage level. In some embodiments, this sequence number is incremented by each indication of the usage level (e.g., each transmission of the UE IP address allocation information IE), or alternatively, the sequence number may be incremented each time the usage level changes.

[0076] The message received in step 702 may include a response message to a request from the CP function regarding the allocation of an IP address to the UE. Examples of this embodiment are shown above in FIGS. 2 and 3 (see, for example, step 3 in those figures). An indication of the usage level may be included in such a message, for example, in response to the usage level exceeding a threshold. In this way, network resources are not utilized to report the usage level until and unless the usage level reaches a value at which there is a possibility that the request to allocate an IP address to the UE may be rejected due to all IP addresses being allocated. Alternatively, the message may be autonomously sent by the UP function. In this case, the message may be received, for example, in response to the usage level exceeding a threshold. Examples of this embodiment are shown below in FIGS. 4 and 5.

[0077] The message received in step 702 may include two or more indications of the usage level (e.g., in the same type of IE), for example, where different UE IP address pools and / or different network instances are included.

[0078] According to some embodiments, if the message received in step 702 includes a response to a request to allocate an IP address to the UE, and the request fails due to the fully allocated range of IP addresses in the UP function, the message may further include an indication that the failure to allocate an IP address to the UE was caused by the exhaustion of the range of IP addresses in the UP function. The indication may include a cause value corresponding to its meaning. See, for example, Table 8.

[0079] In step 704, the CP function selects a UP function to allocate an IP address to the UE based on or in response to the indicated usage level received in step 702. For example, the CP function may adapt the algorithm used to select a UP function to allocate an IP address to the UE. The algorithm may be adapted such that a UP function with a relatively high usage level is less likely to be selected or is selected less frequently than a UP function with a relatively low usage level. In one embodiment, the algorithm may be adapted such that a UP function is not selected to allocate an IP address to the UE. The UP function may be selected based on one or more additional parameters such as the location of the UP function with respect to the CP function or the UE (a UP function closer to the CP function or the UE may be preferred over one further away), the current load of the UP function, the capabilities of the UP function, and the static capacity of the UP function. Those skilled in the art will appreciate that these parameters may be combined in any suitable manner to select a UP function.

[0080] In step 706, the CP function sends a request message to the selected UP function for the UP function to allocate an IP address to the UE.

[0081] FIG. 8 is a block diagram showing an apparatus suitable for use in practicing some embodiments of the present disclosure. For example, any one of the UP function and the CP function described above may be implemented through apparatus 800. As shown, apparatus 800 may include a processor 810, a memory 820 for storing programs, and optionally, a communication interface 830 for communicating data with other external devices through wired and / or wireless communication.

[0082] As described above, the program includes program instructions that, when executed by the processor 810, enable the apparatus 800 to operate in accordance with the embodiments of the present disclosure. That is, the embodiments of the present disclosure may be implemented at least in part by computer software executable by the processor 810, or by hardware, or by a combination of software and hardware. For example, the program instructions may enable the apparatus 800 to implement the method presented in FIG. 6 or perform the signaling of the UP function shown in any of FIGS. 2 to 5, particularly when implementing the UP function. In another example, the program instructions may enable the apparatus 800 to implement the method presented in FIG. 7 or perform the signaling of the CP function shown in any of FIGS. 2 to 5, particularly when implementing the CP function.

[0083] The memory 820 can be of any type suitable for the local technical environment and can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The processor 810 can be of any type suitable for the local technical environment and can include, by way of non-limiting example, one or more of a general-purpose computer, a dedicated computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture.

[0084] FIG. 9 is a block diagram showing a UP entity 900 according to an embodiment of the present disclosure. A range of IP addresses for allocation to UEs can be set in the UP entity 900. As shown in the figure, the UP entity 900 includes a transmission module 902. The transmission module 902 can be set to transmit messages to the control plane core network function, and the messages include an indication of the usage level of the range of IP addresses.

[0085] FIG. 10 is a block diagram showing a CP entity 1000 according to an embodiment of the present disclosure. As shown in the figure, the CP entity 1000 includes a receiving module 1002 and a selection module 1004. The receiving module 1002 may be configured to receive messages from one or more user plane core network functions in which respective ranges of IP addresses for allocation to UEs are set. The message includes an indication of the usage level of the range of IP addresses. The selection module 1004 may be configured to select a user plane core network function to allocate an IP address to the UE based on the indicated usage level.

[0086] The modules described above may be implemented by hardware, or software, or a combination of both.

[0087] Generally, various exemplary embodiments may be implemented in hardware or dedicated circuitry, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software executable by a controller, a microprocessor or other computing device, but the present disclosure is not limited thereto. Various aspects of the exemplary embodiments of the present disclosure may be illustrated and described as block diagrams, flowcharts or using any other graphical representation, but these blocks, devices, systems, techniques or methods described herein are, by way of non-limiting example, hardware, software, firmware, dedicated circuitry or logic, general purpose hardware or a controller or other computing device, or any combination thereof. It should be fully understood that they may be implemented.

[0088] Accordingly, it should be appreciated that at least some aspects of the exemplary embodiments of the present disclosure may be practiced in various components, such as integrated circuit chips and modules. Accordingly, the exemplary embodiments of the present disclosure may be implemented in an apparatus embodied as an integrated circuit, where the integrated circuit may comprise circuitry (and optionally firmware) for embodying at least one or more of a data processor, a digital signal processor, a baseband circuit, and a radio frequency circuit that is configurable to operate in accordance with the exemplary embodiments of the present disclosure.

[0089] It should be appreciated that at least some aspects of the exemplary embodiments of the present disclosure may be embodied in computer-executable instructions, such as one or more program modules executed by one or more computers or other devices. Generally, a program module includes routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer-executable instructions may be stored on a computer-readable medium, such as a hard disk, an optical disk, a removable storage medium, a solid state memory, a RAM, etc. As will be appreciated by those skilled in the art, the functions of the program modules may be combined or distributed as necessary in various embodiments. Further, the functions may be embodied in whole or in part in firmware or hardware equivalents, such as integrated circuits, field programmable gate arrays (FPGAs), etc.

[0090] References in this disclosure to "one embodiment", "an embodiment", etc., indicate that the described embodiment may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described with respect to an embodiment, it is contemplated that it is within the knowledge of one of ordinary skill in the art to implement such feature, structure, or characteristic with respect to other embodiments, whether or not explicitly described.

[0091] For purposes of describing various elements, terms such as "first" and "second" may be used herein, but it should be understood that these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed terms.

[0092] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a", "an" and "the" are to be construed to include the plural forms as well, unless the context clearly dictates otherwise. The terms "comprises", "comprising", "has", "having", "includes" and / or "including" as used herein specify the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. The terms "connect", "connects", "connecting" and / or "connected" as used herein cover both direct and / or indirect connections between two elements.

[0093] The present disclosure includes any novel feature or combination of features disclosed explicitly herein or any generalization thereof. Various modifications and adaptations to the above exemplary embodiments of the present disclosure may become apparent to those skilled in the art in view of the above description when read in conjunction with the accompanying drawings. However, any and all modifications still fall within the scope of the non-limiting and exemplary embodiments of the present disclosure. TIFF0007701434000001.tif255170TIFF0007701434000002.tif110170TIFF0007701434000003.tif255170TIFF0007701434000004.tif255170TIFF0007701434000005.tif77170TIFF0007701434000006.tif255170TIFF0007701434000007.tif125170TIFF0007701434000008.tif255170TIFF0007701434000009.tif125170TIFF0007701434000010.tif174170TIFF0007701434000011.tif233170TIFF0007701434000012.tif255170TIFF0007701434000013.tif255170TIFF0007701434000014.tif57170

Claims

1. A method performed by a user plane (UP) core network function for a wireless communication network, wherein a range of Internet Protocol (IP) addresses for allocation to user equipment (UE) is set in the UP core network function, the method comprising: when a ratio of the occupied IP addresses exceeds a threshold, sending a message to a control plane (CP) core network function, the message including an indication of a usage level of the range of IP addresses; A method including the above.

2. The indication of the usage level of the range of IP addresses includes an indication of a portion of the range of IP addresses allocated to a UE, The method according to claim 1, wherein the indication of the portion of the range of IP addresses allocated to the UE includes a ratio of the range of IP addresses allocated to the UE.

3. The method according to claim 1 or 2, wherein the message further includes a sequence number for the indication of the usage level of the range of IP addresses to enable the CP core network function to distinguish between the current usage level of the range of IP addresses and the previous usage level of the range of IP addresses.

4. The method according to any one of claims 1 to 3, wherein the message includes a Packet Forwarding Control Protocol (PFCP) association update request message.

5. The method further includes obtaining, in the UP core network function, the usage level of the range of IP addresses; when it is determined that the usage level of the range of IP addresses has reached 100%, rejecting a PFCP session establishment request message or no longer responding to a PFCP session establishment request message; The method according to any one of claims 1 to 4, further including the above.

6. The method further includes: receiving a request message from the CP core network function, the message being sent in response to the request message from the CP core network function, the request message indicating that a reporting feature of the usage level of an IP address range is supported by the CP core network function; the method according to any one of claims 1 to 3. **Claim 7**: The method further includes receiving a request message from the CP core network function, wherein the message is transmitted in response to the request message from the CP core network function. The request message from the CP core network function includes a request to assign an IP address to the UE, the message indicates that the assignment of the IP address to the UE has failed, and the message further includes an indication that the assignment of the IP address to the UE has failed due to the lack of an available IP address within the range of IP addresses set in the UP core network function. The method according to any one of claims 1 to 3. **Claim 8**: The indication of the usage level of the range of IP addresses is included in the message transmitted to the CP core network function in response to the usage level of the range of IP addresses exceeding a threshold. The method according to any one of claims 1 to 7. **Claim 9** A method executed by a control plane (CP) core network function for a wireless communication network, the wireless communication network including a user plane (UP) core network function in which a range of Internet protocol (IP) addresses for assignment to a user equipment (UE) is set. The method includes: Receiving, from the UP core network function, a message including an indication of the usage level of the range of IP addresses when the ratio of the occupied IP addresses exceeds a threshold; Selecting a UP core network function to assign an IP address to the UE based at least on the usage level; A method comprising: **Claim 10** The indication of the usage level of the range of IP addresses includes an indication of a portion of the range of IP addresses assigned to the UE; The indication of the portion of the range of IP addresses assigned to the UE includes the ratio of the range of IP addresses assigned to the UE. The method according to claim 9. **Claim 11** The message further includes a sequence number for the indication of the usage level of the range of IP addresses in order to enable the CP core network function to distinguish the current usage level of the range of IP addresses from the previous usage level of the range of IP addresses. The method according to claim 9 or 10, wherein the UP core network function is selected based on a current usage level. **Claim 12** The method according to any one of claims 9 to 11, wherein the message includes a packet forwarding control protocol (PFCP) association update request message. **Claim 13** The method according to any one of claims 9 to 11, further comprising transmitting a request message to the UP core network function and receiving the message in response to the request message transmitted from the CP core network function. **Claim 14** The request message includes a request to assign an IP address to a UE, the message indicates that the assignment of the IP address to the UE has failed, and the message further includes an indication that the assignment of the IP address to the UE has failed due to the lack of available IP addresses within the range of IP addresses set in the UP core network function. The method according to claim 13. **Claim 15** The first UP core network function has a first indicated usage level, the second UP core network function has a second indicated usage level higher than the first indicated usage level, and the CP core network function selects the first UP core network function to assign IP addresses more frequently or with a higher probability than the second UP core network function. The method according to claim 13 or 14. **Claim 16** A network entity implementing a user plane (UP) core network function for a wireless communication network, wherein a range of Internet protocol (IP) addresses for assignment to a user equipment (UE) is set for the UP core network function, and the network entity includes at least one processor (810); and at least one memory (820). comprising at least one memory (820), the at least one memory including instructions executable by the at least one processor (810), whereby the network entity (800) is operable to perform the method according to any one of claims 1 to 8, a network entity.

17. A network entity implementing a control plane (CP) core network function for a wireless communication network, the network entity being comprising at least one processor (810) and at least one memory (820), comprising at least one memory (820), the at least one memory including instructions executable by the at least one processor (810), whereby the network entity (800) is operable to perform the method according to any one of claims 9 to 15, a network entity.

18. A computer-readable storage medium comprising instructions, the instructions being when executed by at least one processor of a network entity implementing a user plane (UP) core network function, to cause the at least one processor to perform the method according to any one of claims 1 to 8, a computer-readable storage medium.

19. A computer-readable storage medium comprising instructions, the instructions being when executed by at least one processor of a network entity implementing a control plane (CP) core network function, to cause the at least one processor to perform the method according to any one of claims 9 to 15, a computer-readable storage medium.

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