Patent Publication Number: US-2023138558-A1

Title: Methods and systems for selecting a user plane function in a wireless communication network

Description:
TECHNICAL FIELD 
     Embodiments discussed herein generally relate to methods and systems for selecting a user plane function when a user equipment (UE) attaches to a wireless communication network. 
     BACKGROUND 
     The fifth generation (5G) technology standard for wireless networks offers faster speeds, greater throughput, and ultra-low latency compared with earlier generations. A 5G network may include the user equipment (UE), the access network including the base station (gNodeB), and the core network. When a UE attempts to attach to a 5G network, the UE may send a session request to the access and mobility management function (AMF), the AMF may select the session management function (SMF), and the SMF may select a user plane function (UPF) to support a protocol data unit (PDU) session between the UE and a data network. The PDU session allows the UE to send data to and receive data from the data network. The UPF may provide an interconnect point between the mobile network infrastructure and the data network, and may be involved in functions such as packet routing and forwarding, and quality of service (QoS) handling. In 4G long-term evolution (LTE) networks, the packet gateway (PGW) function may perform comparable functions to the SMF and the UPF in 5G networks. The mobility management entity (MME) may select the PGW for establishment of an evolved packet switched (EPS) bearer to allow the UE to send data to and receive data from the data network. 
     Wireless communication networks, including 5G networks and 4G LTE networks, may have different sets of user plane functions or PGWs with different throughput or data speed capabilities. For instance, in 5G networks, some user plane functions may have high throughput capabilities but may be costly to operate from the network perspective, while other user plane functions may have lower operation costs and lower throughput capabilities. In addition, some UEs may not be able to exceed certain throughput values. The throughput capabilities of a UE may be limited by various parameters such as the subscriber&#39;s rate plan, the device model of the UE, and/or fair usage policies which may place restrictions on the subscriber&#39;s network usage at certain times. For example, some legacy handsets may not be capable of crossing certain high throughput values, while subscriber rate plans may restrict usage to certain throughput limits. The selection of a high throughput user plane function for a UE with low throughput demands may be a wasteful use of costly network infrastructure. 
     As UE data throughput limits may vary, there is a need for improved methods for selecting the user plane function (e.g., UPF in 5G, or PGW in 4G LTE) to support UE sessions that takes throughput parameters into account. 
     SUMMARY 
     Embodiments disclosed herein provide a technical solution to the problem of selecting a user plane function for a UE session based on throughput parameters, such that higher throughput user plane functions are reserved for UEs having higher throughput demands. In one embodiment, a computer-implemented method for selecting a user plane function for a data or voice session when a user equipment (UE) attaches to a wireless communication network may include receiving a session request from the UE and, at a computer system associated with a management function of the wireless communication network, determining a data throughput limit associated with the UE, identifying a first user plane function having a first data throughput capacity, and identifying a second user plane function having a second data throughput capacity, wherein the first data throughput capacity is higher than the second data throughput capacity. The method may further include selecting the first user plane function if the data throughput limit of the UE is above a predetermined threshold, selecting the second user plane function if the data throughput limit of the UE is below the predetermined threshold, and sending a session request to the selected first or second user plane function. The method may further include establishing the data or voice session between the UE and a data network via the selected first or second user plane function. 
     In another embodiment, a system may include a user equipment (UE), a wireless communication network including a random access network (RAN) and a core network, and a management function in the core network including a computer system. The computer system of the management function may include a processor, a memory, and an input-output circuit. The processor may be configured according to computer-executable instructions for determining a data throughput limit associated with the UE when the UE attempts to attach to the wireless communication network, determining a data throughput capacity of a first user plane function in the wireless communication network, and determining a data throughput capacity of a second user plane function in the wireless communication network, wherein the data throughput capacity of the first user plane function is higher than the data throughput capacity of the second user plane function. The processor may be further configured according to computer-executable instructions for selecting the first user plane function if the data throughput limit of the UE is above a predetermined value, selecting the second user plane function if the data throughput limit of the UE is below the predetermined value, and sending a session request to the selected first or second user plane function to establish a session between the UE and a data network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure may be better understood by reference to the detailed description when considered in connection with the accompanying drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure. 
         FIG.  1    is a schematic representation of a system for selecting a user plane function when a user equipment (UE) attaches to a wireless communication network, according to one embodiment. 
         FIG.  2    is a schematic representation of a computer system of a management function of the system of  FIG.  1   , according to one embodiment. 
         FIG.  3    is a schematic representation of the system of  FIG.  1    when the wireless communication network is a 5G network, according to one embodiment. 
         FIG.  4    is a schematic representation of the system of  FIG.  1    when the wireless communication network is a 4G long-term evolution (LTE) network, according to one embodiment. 
         FIG.  5    is a flow chart of an exemplary computer-implemented method for selecting a user plane function when the UE attaches to the wireless communication network, according to one embodiment. 
         FIG.  6    is a flow chart of another exemplary computer-implemented method for selecting a user plane function when the UE attaches to the wireless communication network, according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings and with specific reference to  FIG.  1   , a system  10  for selecting a user plane function  12  when a user equipment (UE)  14  of a subscriber  16  attempts to attach to a wireless communication network  18  is shown. As detailed more specifically below, the wireless communication network  18  may be a 5G network  20  (see  FIG.  3   ), a 4G long-term evolution (LTE) network  22  (see  FIG.  4   ), or a cellular network of another generation. The wireless communication network  18  may include a radio access network (RAN)  24  including a base station  26 , and a core network  28  including a plurality of user plane functions  12 , a management function  30  involved in selection of the user plane function  12 , and a subscriber management function  32  which carries subscriber information and rate plan information for the UE  14 . 
     The user plane function  12  may be involved in establishment of a session  34  between the UE  14  and a data network  36  (e.g., the Internet or IP Media Subsystem (IMS)), allowing the UE  14  to send data to and receive data from the data network  36 , such as during a voice call or while browsing the Internet. The user plane functions  12  may have different throughput capacities related to their respective data processing speeds. The number of user plane functions  12  available for selection may vary depending on the network architecture. In one non-limiting embodiment, the network  18  may include hundreds of user plane functions  12 . As used herein, the user plane function  12  may include a user plane function (UPF) in 5G, a packet gateway function (PGW) in 4G LTE, or a comparable network function of another cellular network generation. Additionally, as used herein, the management function  30  may include a session management function (SMF) in 5G, a mobility management entity (MME) in 4G LTE, or a comparable network function of another cellular network generation. 
     As explained further below, the management function  30  may select an appropriate user plane function  12  for establishment of the session  34  based on a limit in a data throughput value of the UE  14  and the throughput capabilities of the user plane functions  12 . The management function  30  may obtain information related to the data throughput limit of the UE  14  from the subscriber management function  32 . If the limit in the data throughput value of the UE  14  is determined to be low (below a threshold value), the management function  30  may select a user plane function  12  with a lower throughput capacity. If the limit in the data throughput value is determined to be high (above the threshold value), the management function  30  may select a user plane function  12  with a higher throughput capacity. This allows the network  18  to place UEs  14  with lower data throughput values with lower throughput user plane functions  12 , reserving more costly higher throughput user plane functions  12  for UEs  14  likely to have higher throughput demands. 
     A schematic representation of a computer system  38  of the management function  30  is shown in  FIG.  2   . The computer system  38  may include one or more processors  40  configured according to computer-executable instructions involved in selection of the user plane function  12 . The computer system  38  may further include a memory  42  configured to store the computer-executable instructions and assist the processor  40 . The memory  42  may include a random access memory (RAM)  44 , or volatile memory for temporary storage, and a read-only memory (ROM)  46 , or non-volatile memory for permanent storage. An input-output circuit  48  of the computer system  38  may enable the computer system  38  to communicate with other entities of the network  18 , such as the user plane functions  12  and the subscriber management function  32 . 
       FIG.  3    shows an embodiment of the system  10  when the wireless communication network  18  is a 5G network  20 . In this arrangement, the user plane functions  12  are UPFs  50 , the management function  30  is an SMF  52 , and the subscriber management function  32  is a unified data management function (UDM)  54 . The 5G network  20  may include an access network  24  (including the base station  26  or gNodeB), and the core network  28 . Among other entities not shown for clarity, the core network  58  may include an access and mobility management function (AMF)  60 , the SMF  52 , the UDM  54 , and the UPFs  50  having variable throughput capacities. 
     When the UE  14  attempts to attach to the network  20 , it may send a session request to the AMF  60 , and the AMF  60  may select the SMF  52 . The SMF  52  may communicate with the UDM  54  to obtain subscription information and other information about the UE  14 , and begin the process of selecting an appropriate UPF  50  to support the session  34 . The UPFs  50  may inform the SMF  52  of their respective throughput capabilities. For example, each UPF  50  may communicate one or more signals to the SMF  52  informing the SMF  52  of whether the respective UPF  50  is a low throughput UPF (with a throughput capacity below a threshold value), or a high throughput UPF (with a throughput capacity above a threshold value). 
     Based on the information obtained from the UDM  54 , the SMF  52  may determine a data throughput limit for the UE  14 . The data throughput limit may be limited based on the subscriber&#39;s rate plan, a device model of the UE  14 , or other parameters such as fair usage policies. If the data throughput limit of the UE  14  is above a predetermined threshold, the SMF  52  may select a high throughput UPF  50  for establishment of the session  34 . If, on the other hand, the data throughput limit of the UE  14  is below the predetermined threshold, the SMF  52  may select a low throughput UPF for establishment of the session  34 . 
     An embodiment of the system  10  when the wireless communication network  18  is a 4G LTE network  22  is shown in  FIG.  4   . In the context of the 4G LTE network  22 , the user plane functions  12  are PGWs  62 , the management function  30  is the mobility management entity (MME)  64 , and the subscriber management function  32  is a home subscriber server (HSS)  66 . In some embodiments of the 4G LTE network  22  having control and user plane separation in place, the PGWs  62  for selection may be user plane PGWs (PGW-Us). The 4G LTE network  22  may include the radio access network  24  (including the base station  26  or eNodeB), and the core network  28  referred to as the evolved packet core (EPC)  68 . Among other elements not shown for clarity, the EPC  68  may include the MME  64 , the HSS  66 , a domain name server (DNS)  70 , and the PGWs  62  having different throughput capacities. The MME  64  may apply logic to select the PGW  62  for creating the session  34  as described below. 
     When the UE  14  attempts to attach to the network  22 , the MME  64  may receive a session request from the base station  26 . The MME  64  may query the HSS  66  to obtain subscription information and other information for the UE  14  to determine the data throughput limit of the UE  14 . The MME  64  may also query the DNS  70  to obtain throughput capacity information for each of the available PGWs  62 . The throughput capacity information for the PGWs  62  may indicate whether each available PGW  62  is a low throughput PGW with a throughput capacity below a threshold value, or a high throughput PGW with a throughput capacity above a threshold value. If the UE  14  has a low data throughput limit (below a predetermined threshold), the MME  64  may select a matching low throughput capacity PGW  62  to create the session  34 . Alternatively, if the UE  14  has a high data throughput limit (above a predetermined threshold), the MME  64  may select a matching high throughput capacity PGW  62  to create the session  34 . In some embodiments of the 4G LTE network having control and user plane separation, this logic may be applied by the PGW-C instead of the MME  64  for selection of a PGW-U. 
     Turning to  FIG.  5   , a computer-implemented method for selecting the user plane function  12  when the UE  14  attaches to the network  18  is shown. The method may be performed by the processor  40  of the management function  30  of  FIG.  2   . The method of  FIG.  5    encompasses UE attachment in the 5G network  20 , the 4G LTE network  22 , or a cellular network of another generation. At a first block  80 , the management function  30  may receive a session request when the UE  14  attempts to attach to the network  18 . At a block  82 , the management function  30  may receive information regarding the throughput capacities of each of the user plane functions  12  available for creation of the session  34 . For instance, in the 5G network  20 , the UPFs  12  may inform the SMF  52  of their respective throughput capacities. In the 4G LTE network  22 , the MME  64  may obtain information regarding the throughput capacities of the PGWs  62  from the DNS  70  or another network function. The user plane functions  12  may be classified or ranked according to their throughput capacities, with those user plane functions  12  having throughput capacities below a threshold value being classified as low throughput user plane functions, and those user plane functions  12  having throughput capacities above a threshold value being classified as high throughput user plane functions. This classification may be made at the management function  30 , or at other functions of the network  18  (e.g., the user plane functions, the DNS, etc.). The threshold values which classify the user plane functions  12  as low or high throughput may vary depending on the design of the network  18 . 
     At blocks  84  and  86 , the management function  30  may determine the data throughput value limit for the UE  14  by querying the subscriber management function  32 , and determining the data throughput limit based on the information obtained in response to the query. The information may include details in the subscriber&#39;s rate plan, information regarding the device model of the UE  14 , and/or any fair usage policies applied to the UE  14 . For instance, the subscriber&#39;s rate plan may have a certain data speed limit such as 1 gigabits per second (Gbps) or 5 Gbps. In one embodiment, information regarding the device model of the UE  14  may be obtained from an international mobile equipment identity (IMEI) number of the UE  14 . The block  86  may involve determining whether the data throughput of the UE  14  is limited by the rate plan associated with the UE  14 , the device model of the UE  14 , or any other factors that may limit the data speed of the UE  14  such as fair use policies, the location of the UE  14 , how many customers are using the same cell site, or device software and number of applications on the UE  14 . In one example, the UE  14  may have a high speed rate plan but may be a legacy handset limited to a lower data throughput limit. In this case, the data throughput limit of the UE  14  is determined based on the data speed limit of the device model which is the limiting parameter. In another example, the UE  14  may be a newer handset capable of high throughput values, but the subscriber rate plan may be limited to lower data speeds. In the latter case, the data throughput limit of the UE  14  is determined based on the data speed limit in the subscriber rate plan which is the limiting parameter. 
     If the data throughput limit of the UE  14  is above a predetermined threshold (as assessed at a block  88 ), the management function  30  may select a high throughput user plane function  12  for the session  34 , and send a session request to the selected high throughput user plane function  12  (blocks  90  and  92 ). If, however, the data throughput limit of the UE  14  is below the predetermined threshold (as assessed at the block  88 ), the management function  30  may select a low throughput user plane function  12  for the session  34 , and send a session request to the selected low throughput user plane function  12  (blocks  94  and  96 ). 
     Another computer-implemented method for selecting the user plane function  12  as performed by the processor  40  of the management function  30  is shown in  FIG.  6   . The method may be performed in the context of the 5G network  20 , the 4G LTE network  22 , or a cellular network of another generation. At a first block  100 , the management function  30  may receive a session request when the UE  14  attempts to attach to the network. At blocks  102  and  104 , the management function  30  may identify a first user plane function  12  with a first user throughput capacity (block  102 ), and a second user plane function  12  with a second user throughput capacity (block  104 ), wherein the first user plane function  102  has a higher throughput capacity than the second user plane function  104 . For example, in the context of the 5G network  20 , the first and second user plane functions  102  and  104  may be identified by signals received from the UPFs  50  informing the SMF  52  of their respective throughput capacities. Alternatively, in the context of the 4G LTE network  22 , the MME  64  may query the DNS  70  or another network function for the throughput capacities of the PGWs  62 . 
     At a block  106 , the management function  30  may obtain data throughput information for the UE  14  by querying the subscriber management function  32 . The information may include the throughput limit in the subscriber&#39;s rate plan, the device model of the UE  14  (which may be determined based on the IMEI tag of the UE  14 ), and/or any fair usage policies applied to the UE  14 . The management function  30  may also obtain additional information which may be applicable to determining the data throughput limit of the UE  14 , such as the location of the UE  14 , the number of other customers using the same cell site, and/or the software or applications installed on the UE  14 . Such additional information may be gathered via the subscriber management function  32  (e.g., the UDM  54  or the HSS  66 ), via information at the management function  30  itself, or from another function of the network. Based on the gathered information, the management function  30  may determine a data throughput limit for the UE  14  (block  108 ). As explained above, the block  108  may involve determining a limiting parameter which restricts the UE  14  from surpassing a certain throughput value (e.g., rate plan, device model, etc.), and determining the data throughput limit based on the limiting parameter. 
     If the data throughput limit of the UE  14  is above a predetermined threshold (as assessed at a block  110 ), the management function  30  may select the first user plane function  12  having the higher throughput capacity for establishing the session  34  (block  112 ). The management function  30  may then send a session request to the first user plane function  12  to establish the session  34  between the UE  14  and the data network  36  (block  114 ). If, on the other hand, the data throughput limit of the UE  14  is below the predetermined threshold (as assessed at the block  110 ), the management function  30  may select the second user plane function  12  having the lower throughput capacity for establishing the session  34  (block  116 ). A session request may then be sent to the second user plane function  12  to establish the session  34  between the UE  14  and the data network  36  (block  118 ). It will be understood that the order of the steps in  FIGS.  5 - 6    is exemplary, and that the steps may be carried out in different orders or simultaneously in practice. 
     In other embodiments, the user plane functions  12  may have a range of classifications with more granularity, such as low, medium, and high throughput user plane functions. In such embodiments, the management function  30  may apply logic to match the data throughput limit of the UE  12  to a user plane function having a compatible throughput capacity whether it be low, medium, or high. In yet other embodiments, the management function  30  may match the data throughput value limit of the UE  14  to a user plane function  12  having a compatible throughput capacity based on raw or treated numbers of the respective throughput capabilities. Additionally, in yet other embodiments, the management function  30  may select the user plane function  12  based on the current load on the available user plane functions  12 . If, for example, the UE  14  has a high data throughput value limit, the management function  30  may select a user plane function  12  which is currently serving fewer UEs to establish the session for the UE  14 , regardless of the throughput capacity of the user plane function  12 . In some embodiments, the management function  30  may take into account both the throughput capacities and the current load on the user plane functions  12  when making its selection. 
     As is encompassed by the embodiments of  FIGS.  1  and  5 - 6   , the concepts of the present disclosure may be extended to include selection of comparable user plane functions involving cellular network generations that are not yet developed. In such situations, the concept of selecting the user plane function based on the data throughput limit of the UE and the throughput capacity of the user plane function may still apply. 
     The present disclosure provides a technical solution to the problem of selecting more costly user plane functions for UEs with lower throughput limits. According to the present disclosure, UEs having lower throughput limits may be sent to user plane functions having lower throughput capacities. In this way, the lower throughput user plane functions may serve more UEs, reserving the more costly higher throughput user plane functions for UEs having higher throughput demands. A parameter (rate plan, UE model, etc.) which restricts the UE from crossing certain throughput parameters may be identified to determine the data throughput limit of the UE. A user plane function with a compatible throughput capability (e.g., low, high, etc.) is then selected for establishment of the session.