Patent Publication Number: US-2023164654-A1

Title: User equipment (ue) roaming based on network performance

Description:
RELATED CASES 
     This United States patent application is a continuation of U.S. patent application Ser. No. 17/146,644 that was filed on Jan. 12, 2021 and is entitled “USER EQUIPMENT (UE) ROAMING BASED ON NETWORK PERFORMANCE.” U.S. patent application Ser. No. 17/146,644 is hereby incorporated by reference into this United States patent application. 
    
    
     TECHNICAL BACKGROUND 
     Wireless communication networks provide wireless data services to wireless user devices. Exemplary wireless data services include machine-control, internet-access, media-streaming, and social-networking. Exemplary wireless user devices comprise phones, computers, vehicles, robots, and sensors. The wireless communication networks have wireless access nodes that exchange wireless signals over frequency channels with the wireless user devices using wireless network protocols. Exemplary wireless network protocols include Institute of Electrical and Electronic Engineers (IEEE) 802.11 (WIFI), Long Term Evolution (LTE), Fifth Generation New Radio (5GNR), Millimeter Wave (MMW) and Low-Power Wide Area Network (LP-WAN). 
     Wireless user devices register with the wireless communication networks to receive the wireless data services. The wireless communication network that a wireless user device is registered with is referred to as a “home wireless network.” When the wireless user device is unable to establish a wireless connection with its home wireless network, the wireless user device will typically attach to a different wireless communications network referred to as a “visitor wireless network.” When the wireless user device is served by the visitor wireless network, the wireless user device is roaming. Typically, wireless user devices will roam when the signal strength of the home wireless network is too weak for wireless data services. 
     When wireless user devices attach to a wireless access node, the wireless access node becomes loaded. An increase in load decreases the ability of the wireless access node to provide wireless data service to the wireless user devices. With the increase in the amount of wireless user devices, the load in the wireless access nodes has also increased. The wireless user devices are faced with the problem of trying to receive wireless data services with the increase in load. Moreover, wireless user devices which subscribe to premium wireless data services struggle to receive their premium services from heavily loaded networks. Unfortunately, the wireless user devices do not effectively and efficiently roam given the increase in load. 
     TECHNICAL OVERVIEW 
     A wireless user device selects wireless networks. The wireless user device determines signal strength for the wireless networks and identifies candidate ones of the wireless networks based on their signal strength. The wireless user device obtains performance information for the candidate wireless networks that comprises data throughput, error rate, band fading, and/or intermodulation. The wireless user device selects one of the candidate wireless networks based on the performance information. The wireless user device wirelessly exchanges data with the selected one of the candidate wireless networks. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a wireless User Equipment (UE) to hand over to a roaming wireless network based on network performance. 
         FIG.  2    illustrates an exemplary operation of the wireless UE to hand over to a roaming wireless network based on network performance. 
         FIG.  3    illustrates an exemplary operation of the wireless UE to hand over to a roaming wireless network based on network performance. 
         FIG.  4    illustrates a Fifth Generation New Radio (5GNR)/Long Term Evolution (LTE) UE and a Fifth Generation (5G) UE to hand over to a roaming wireless network based on network performance. 
         FIG.  5    illustrates the 5GNR/LTE UE to hand over to a roaming wireless network based on network performance. 
         FIG.  6    illustrates the 5G UE to hand over to a roaming wireless network based on network performance. 
         FIG.  7    illustrates a home LTE eNodeB to facilitate the handover of the 5GNR/LTE UE. 
         FIG.  8    illustrates a home 5GNR gNodeB to facilitate the handover of the 5G UE. 
         FIG.  9    illustrates an exemplary operation of the 5GNR/LTE UE, the home LTE eNodeB, and a home LTE Evolved Packet Core (EPC) to hand over the 5GNR/LTE UE based on network performance. 
         FIG.  10    illustrates an exemplary operation of the 5G UE, the home 5GNR gNodeB, and a home 5GNR Fifth Generation Core (5GC) to hand over the 5G UE based on network performance. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    illustrates wireless communication networks  100 . Wireless communication networks  100  provide wireless data services to UE  101  like machine-control, internet-access, media-streaming, social-networking, and/or some other type of wireless networking product. Wireless communication networks  100  comprise wireless UE  101 , links  103 - 112 , home access node  140 , roaming access nodes  141 - 142 , home network elements  150 , and roaming network elements  151 - 152 . Wireless UE  101  comprises UE radio  120  and UE processing circuitry  130 . 
     Various examples of network operation and configuration are described herein. In some examples, UE radio  120  wirelessly transfers UE capabilities of UE  101  to home access node  140 . Radio  120  wirelessly receives performance information from home access node  140  for the home access node  140  and performance information for roaming access nodes  141 - 142 . Radio  120  measures signal strengths for roaming access nodes  141 - 142 . Radio  120  transfers the performance information to UE processing circuitry  130 . Radio  120  transfers the signal strengths for roaming access nodes  141 - 142  to UE processing circuitry  130 . UE processing circuitry  130  receives the signal strengths for roaming access nodes  141 - 142  and the performance information for home access node  140  and roaming access nodes  141 - 142 . UE processing circuitry  130  determines candidate roaming access nodes from roaming access nodes  141 - 142  based on the signal strengths. For example, UE processing circuitry  130  may determine that roaming access node  141  is a candidate roaming access node when the signal strength of roaming access node  141  is strong enough to support wireless data services. UE processing circuitry  130  determines performance differentials between home access node  140  and the candidate roaming access nodes based on the performance information for home access node  140  and the performance information for the candidate roaming access nodes. For example, UE processing circuitry  130  may utilize a data structure to compare the network throughput for home access node  140  to the network throughputs for roaming access nodes  141 - 142  to determine the performance differentials. UE processing circuitry  130  ranks the candidate roaming access nodes based on the performance differentials. When at least one of the performance differentials exceeds a performance differential threshold, UE processing circuitry  130  generates a handover request to attach to the candidate roaming access node with the largest performance differential. UE processing circuitry  130  transfers the handover request to UE radio  120 . UE radio  120  wirelessly transfers the handover request to the home access node  140 . Advantageously, UE  101  effectively and efficiently generates a handover request to attach to a roaming wireless access node in response to network performance differentials between the home and roaming wireless access nodes. 
     UE  101  comprises antennas, amplifiers, filters, modulation, analog/digital interfaces, microprocessors, software, memories, transceivers, bus circuitry, and the like. Access nodes  140 - 142  and network elements  150 - 152  comprise microprocessors, memories, software, transceivers, bus circuitry, and the like. The microprocessors comprise Digital Signal Processors (DSP), Central Processing Units (CPU), Graphical Processing Units (GPU), Application-Specific Integrated Circuits (ASIC), and/or the like. The memories comprise Random Access Memory (RAM), flash circuitry, disk drives, and/or the like. The memories store software like operating systems, user applications, radio applications, and network applications. The microprocessors retrieve the software from the memories and execute the software to drive the operation of wireless communication networks  100  as described herein. Although UEs  101  is depicted as a smartphone, UE  101  might instead comprise a computer, robot, vehicle, or other data appliances with wireless communication circuitry. 
     Access nodes  140 - 142  comprise Fifth Generation New Radio (5GNR) gNodeBs, Millimeter Wave (MMW) access nodes, Fifth Generation Radio Access Technology (5G RAT) nodes, Evolved Universal Terrestrial Radio Access Network Dual Connectivity (EN-DC) nodes, 5G EN-DC access nodes, Long Term Evolution (LTE) eNodeBs, WIFI hotspots, Low-Power Wide Area Network (LP-WAN) nodes, and/or some other wireless network apparatus. Access nodes  140 - 142  are geographically dispersed, however access nodes  140 - 142  may be co-located. Network elements  150 - 152  comprise User Plane Functions (UPFs), Access and Mobility Management Function (AMFs), System Architecture Evolution Gateways (SAE GWs), Mobility Management Entities (MMEs), and/or some other network apparatus. Access nodes  140 - 142  are depicted as towers, but access nodes  140 - 142  may use other mounting structures or no mounting structure at all. 
     Wireless links  103 - 105  use over-the-air air electromagnetic frequencies in the low-band, mid-band, high-band, or some other portion of the electromagnetic spectrum. Wireless links  103 - 105  use protocols like 5GNR, LTE, MMW, Institute of Electrical and Electronic Engineers (IEEE) 802.11 (WIFI), LP-WAN, and/or some other format of wireless protocol. Links  106 - 112  use metal, glass, air, or some other media. Links  106 - 112  use IEEE 802.3 (Ethernet), Time Division Multiplex (TDM), Data Over Cable System Interface Specification (DOCSIS), Internet Protocol (IP), Hypertext Transfer Protocol (HTTP), Fifth Generation Core (5GC), 5GNR, LTE, WIFI, virtual switching, inter-processor communication, bus interfaces, and/or some other data communication protocols. Links  103 - 112  may comprise intermediate network elements like relays, routers, and controllers. 
       FIG.  2    illustrates an exemplary operation of UE  101  to hand over to a roaming access node based on network performance. In other examples, the operation and structure of wireless UE  101  may be different. UE radio  120  wirelessly transfers UE capabilities to home access node  140  ( 201 ). UE radio  120  wirelessly receives performance information for roaming access nodes  141 - 142  and home access node  140  from home access node  140  and transfers the performance information to UE processing circuitry  130  ( 202 ). For example, the performance information may indicate network error rate, network throughput, and/or other network performance indicators for access nodes  140 - 142 . UE radio  120  measures the signal strengths for roaming access nodes  141 - 142  and transfers the signal strengths to processing circuitry  130  ( 203 ). 
     UE processing circuitry  130  receives the performance information for roaming access nodes  141 - 142  and home access node  140  from UE radio  120  ( 204 ). UE processing circuitry  130  receives the signal strengths for roaming access nodes  141 - 142  from UE radio  130  ( 205 ). UE processing circuitry  130  determines candidate roaming access nodes based on the signal strengths for roaming access node  141 - 142  ( 206 ). For example, UE processing circuitry  130  may apply the received signal strengths to a signal strength threshold to determine the candidate roaming access nodes. UE processing circuitry  130  determines performance differentials between home access node  140  and the candidate roaming access nodes based on the performance information. For example, UE processing circuitry  130  may determine the difference in network throughput between the candidate roaming access nodes and home access node  140 . UE processing circuitry  130  ranks the candidate roaming access nodes by performance differential ( 207 ). When at least one of the performance differentials exceeds a performance differential threshold, UE processing circuitry  130  generates a handover request to attach to the candidate roaming access node with the largest performance differential and transfers the handover request to UE radio  120  ( 208 ). UE radio  120  wirelessly transfers the handover request to home access node  140  ( 209 ). 
       FIG.  3    illustrates an exemplary operation of UE  101  to hand over to a roaming access node based on network performance. In other examples, the operation and structure of UE  101  may differ. In this example, UE  101  hands over to a roaming access node based on network performance differentials between a home access node and roaming access nodes. 
     In operation, UE processing circuitry  130  transfers UE capabilities for UE  101  to UE radio  120 . UE radio  120  wirelessly transfers the UE capabilities to home access node  140 . In response to receiving the UE capabilities for UE  101 , home access node  140  retrieves performance information for roaming access nodes  141 - 142  from home network elements  150 . Home access node  140  wirelessly transfers the performance information for the roaming access nodes and performance information for itself to UE processing circuitry  130  over UE radio  120 . For example, the performance metrics may indicate network throughput, network error rate, or some other performance indicator for roaming access nodes  141 - 142  and home access node  140 . UE processing circuitry  130  directs UE radio  120  to measure the signal strength for roaming access nodes  141 - 142 . UE radio  120  measures the signal strengths for roaming access nodes  141 - 142  and transfers the signal strengths to UE processing circuitry  130 . 
     UE processing circuitry determines candidate roaming access nodes out of roaming access nodes  141 - 142  based on the signal strengths. For example, processing circuitry  130  may determine the received signal strength for roaming access node  142  is sufficient for data services and responsively determine that roaming access node  142  is a candidate roaming access node. Likewise, processing circuitry  130  may determine that the signal strength for roaming access node  141  is insufficient for wireless data services and responsively determine that roaming access node  141  is not a candidate roaming access node. When UE processing circuitry  130  determines that a roaming access node is not a candidate roaming access node, UE processing circuitry  130  does not attempt to attach to that roaming access node. UE processing circuitry  130  determines performance differentials between home access node  140  and the candidate roaming access nodes of roaming access nodes  141 - 142 . The performance differentials may indicate differences in network throughput, network error rate, or some other network performance indicator between home access node  140  and the candidate roaming access nodes of roaming access nodes  141 - 142 . UE processing circuitry  130  ranks the candidate roaming access nodes by performance differential. Typically, UE processing circuitry  130  ranks candidate roaming access nodes with larger performance differentials higher than candidate roaming access nodes with smaller performance differentials. 
     UE processing circuitry  130  generates a handover request to attach to the roaming access node with the largest performance differential when the performance differentials exceed a performance differential threshold. In some examples, UE processing circuitry  130  determines that a Guaranteed Bit Rate (GBR) application is active on UE  101  and may responsively generate a handover request when the performance differential threshold is exceeded and the GBR application is active. In some examples, UE processing circuitry  130  determines that a UE hotspot capability is active on UE  101  and may responsively generate a handover request when the performance differential threshold is exceeded, and the UE hotspot capability is active. In some examples, UE processing circuitry  130  determines the antenna type of the candidate roaming access nodes and the antenna type of UE radio  120  and responsively generates a handover request when the performance differential threshold is exceeded, and the antenna types are the same. UE processing circuitry  130  transfers the handover request to home access node  140  over UE radio  120 . Home access node forwards the handover request to roaming access nodes  141 - 142  over home network elements  150 . Home network elements  150  typically transfers the handover request to roaming access nodes  141 - 142  over roaming network elements  151 - 152  however roaming network elements  151 - 152  are omitted for clarity. The selected candidate roaming access node of roaming access nodes  141 - 142  accepts the handover request. UE processing circuitry  130  exchanges user signaling over UE radio  120  with the selected candidate roaming access node to attach to the candidate roaming access node. UE processing circuitry  130  exchanges user data with the selected roaming access node. 
       FIG.  4    illustrates Fifth Generation New Radio (5GNR) Long Term Evolution (LTE) networks  400  to hand over UEs  410  based on network performance differences. 5GNR/LTE networks  400  are an example of wireless communication networks  100 , although networks  100  may differ. 5GNR/LTE networks  400  comprise 5GNR/LTE UE  410 , 5G UE  411 , home LTE eNodeB  430 , roaming 5GNR gNodeBs  431 - 432 , home 5GNR gNodeB  433 , roaming 5GNR gNodeB  4235 , roaming 5G RAT node  435 , home Evolved Packet Core (EPC)  440 , roaming Fifth Generation Cores (5GCs)  441 - 442 , home 5GC  443 , and roaming 5GCs  444 - 445 . LTE/5GNR UE  410  comprises LTE radio  420 , 5GNR radio  421 , and user circuitry  422 . 5G UE  411  comprises 5GNR radio  423 , 5G RAT radio  424 , and user circuitry  425 . 
     EPC  440  and 5GCs  441 - 445  comprise Network Function Virtualization Infrastructure (NFVI) hardware, NFVI hardware drivers, NFVI operating systems, NFVI virtual layers, and NFVI Virtual Network Functions (VNFs), however individual structures depicting the NFVI systems of EPC  440  and the NFVI systems of 5GCs  441 - 445  are omitted for clarity. The NFVI hardware typically comprises Network Interface Cards (NIC), CPU, RAM, flash/disk drives, and data switches (SW). The NFVI hardware drivers typically comprise software that is resident in the NIC, CPU, RAM, DRIVE, and SW. The NFVI operating systems typically comprise kernels, modules, applications, containers, hypervisors, and the like. The NFVI virtual layers comprises virtual NICs (vNIC), virtual CPUs (vCPU), virtual RAM (vRAM), virtual Drives (vDRIVE), and virtual Switches (vSW). The NFVI VNFs typically comprise LTE MME, LTE SAE GW, LTE PCRF, LTE HSS, 5GC AMF, 5GC UPF, 5GC SMF, 5GC AUSF, 5GC PCF, 5GC UDM and/or other LTE and 5GC VNFs. The NFVI hardware in EPC  440  and 5GCs  441 - 445  executes the NFVI hardware drivers, the NFVI operating systems, the NFVI virtual layers, and the NFVI VNFs to serve UEs  410 - 411 . 
     In operation, UE  410  attaches to home LTE eNodeB  430  over LTE radio  420 . User circuitry  422  transfers UE capabilities of UE  410  to home LTE eNodeB  430  over LTE radio  420 . The UE capabilities indicate Public Land Mobile Networks (PLMNs) that UE  410  can attach to. Home LTE eNodeB  430  requests data service for UE  410  from home EPC  440  over S1-MME signaling and indicates the UE capabilities of UE  410 . Home EPC  440  authenticates and authorizes LTE/5GNR UE  410  for wireless data services that are represented by Access Point Names (APNs). Home EPC  440  selects Access Point Names (APNs), Quality-of-Service Class Identifiers (QCIs), and network addresses for UE  410  based on the APNs. In response to the UE capabilities, home LTE EPC  440  retrieves network performance information for the PLMNs indicated in the UE capabilities from roaming 5GCs  441 - 442 . Home LTE EPC  440  transfers the APNs, QCIs, network address, and performance information for UE  410  to home LTE eNodeB  430 . Home EPC  440  exchanges user data for UE  410  with external systems and with Home LTE eNodeB  430 . Home LTE eNodeB  430  transfers the APNs, QCIs, network address to user circuitry  422  over LTE radio  420 . Home LTE eNodeB  430  exchanges the user data with user circuitry  422  over LTE radio  420 . 
     User circuitry  422  directs 5GNR radio  421  to measure signal strengths for roaming 5GNR gNodeBs  431 - 432 . 5GNR radio  421  transfers the signal strengths for roaming 5GNR gNodeBs  431 - 432  to user circuitry  422 . User circuitry  422  determines candidate roaming access nodes based on the signal strengths of roaming 5GNR gNodeBs  431 - 432 . Typically, user circuitry  422  selects roaming access nodes with received signal strength capable of supported wireless data services as candidate roaming access nodes. User circuitry  422  determines network performance differentials between home LTE eNodeB  430  and roaming 5GNR gNodeBs  431 - 432 . For example, the network performance differentials may indicate differences between home LTE eNodeB  430  and roaming 5GNR gNodeBs  431 - 432  in network error rate, throughput, band fading, intermodulation, interference, and/or other network performance indicators. User circuitry  422  ranks the candidate roaming access nodes based on network performance differential. Typically, user circuitry  422  ranks candidate roaming access nodes with a larger performance differential higher than candidate roaming access nodes with a smaller performance differential. 
     When at least one of the network performance differentials exceed a performance differential threshold, user circuitry  422  generates a handover request to attach to the candidate roaming access node with the largest performance differential. In some examples, user circuitry  422  may generate a handover request in response to other triggering events in addition to the exceeded performance differential threshold. For example, user circuitry  422  may determine that a Guaranteed Bit Rate (GBR) application is active, a UE WiFi hotspot capability is active, and/or other triggering events are active and responsively generate a handover request when the performance differentials exceed a performance differential threshold. 
     User circuitry  422  transfers the handover request to attach to the selected candidate roaming access node to home LTE eNodeB  430  over LTE radio  420 . Home LTE eNodeB  430  transfers the handover request to home EPC  440 . Home EPC  440  routes the handover request to the roaming 5GC associated with the selected candidate roaming access node. For example, if the handover request indicates the selected candidate roaming access node is roaming 5GNR gNodeB  431 , then home EPC  440  routes the handover request to roaming 5GC  441 . The selected roaming 5GC accepts the request. Home EPC  440  directs home LTE eNodeB  430  to notify user circuitry  422 . Home LTE eNodeB  430  transfers a notification to LTE radio  420  that indicates that the handover request has been accepted. LTE radio  420  transfers the notification to user circuitry  422 . 
     User circuitry  422  directs LTE radio  420  to detach from home LTE eNodeB  430  and directs 5GNR radio  421  to attach to the selected candidate roaming access node of roaming access nodes  431 - 432 . User circuitry  422  exchanges attachment signaling with the selected candidate roaming access node over 5GNR radio  421 . User circuitry  422  exchanges user data with the selected candidate roaming access node over 5GNR radio  421 . 
     In some examples, user circuitry  422  stores a PLMN list of PLMNs that UE  410  can attach to and receive wireless communications service. The PLMN list may indicate network performance information for each of the PLMNs and the access nodes associated with the PLMNs. For example, the performance information may indicate network throughput, network error rate, band fading, interference level, and/or other performance information associated with the PLMNs. The PLMN list may further indicate performance differential thresholds for each of the available PLMNs. User circuitry  422  updates the performance information in the PLMN list when user circuitry  422  receives new PLMN data. User circuitry  422  may receive new PLMN data over System Information Blocks (SIBs) broadcast by home LTE eNodeB  430  and roaming 5GNR gNodeBs  431 - 432 . User circuitry  422  may determine new PLMN data when UE  410  is attached to one of the PLMNs. For example, user circuitry  422  may measure network throughput for home LTE eNodeB  430  and store the network throughput for the PLMN of LTE eNodeB  430  in the PLMN list. User circuitry  422  may utilize the stored performance information from the PLMN list to determine the network performance differentials. For example, home LTE eNodeB  430  may not be able to provide network performance information for each of the available PLMNs and user circuitry  422  may instead use the PLMN list to determine the performance information. In some examples, user circuitry  422  comprises a Subscriber Identity Module (SIM) and the SIM of user circuitry  422  stores the PLMN list. 
     Note 5GNR gNodeBs  433 - 434  and 5G RAT node  435  use different types of 5G Radio Access Technology (RAT). The different types of 5G RAT may have different frequency channel sizes, frequency levels, resource block time intervals, and resource block bandwidths. For example, home 5GNR gNodeB  433  may provide an enhanced voice calling service with unique time intervals and bandwidths while roaming 5G RAT node  435  may provide an enhanced video broadcast service with unique time intervals and bandwidths while. Some 5G UEs are not capable of using each type of 5G technology from 5GNR gNodeB  433 - 434  and 5G RAT node  435 , but 5G UE  411  is capable of using each type of 5G RAT. 
     User circuitry  425  in 5G UE  411  directs 5GNR radio  423  to attach to home 5GNR gNodeB  433  and to indicate the UE capabilities of 5G UE  411 . The UE capabilities indicate PLMNs that 5G UE  411  can use for wireless data services. 5GRN radio  423  wirelessly attaches to home 5GNR gNodeB  433  and indicates the UE capabilities of 5G UE  411 . Home 5GNR gNodeB  433  requests data service from 5GC  443  and indicates the capabilities of UE  411  to 5GC  443  over N2 signaling. Home 5GC  443  authenticates and authorizes 5G UE  411  for data services. In response to the UE capabilities, home 5GC  443  retrieves network performance information for the PLMNs indicated in the UE capabilities from roaming 5GCs  444 - 445 . Home 5GC  443  transfers quality-of-service metrics and network addressing for UE  411  and network performance information of roaming 5GCs  444 - 445  and home 5GC  443  to home 5GNR gNodeB  433 . home 5GNR gNodeB  433  transfers the selected quality-of-service metrics, network addresses, and network performance information to user circuitry  425  or 5GNR radio  423 . Home 5GNR gNodeB  433  wirelessly exchanges user data with user circuitry  425  over 5GNR radio  423 . 
     User circuitry  425  directs 5GNR radio  423  to measure signal strength for roaming 5GNR gNodeB  434  and directs 5G RAT radio  424  to measure signal strength for roaming 5G RAT node  435 . 5GNR radio  423  and 5G RAT radio  424  transfer the signal strengths for to user circuitry  425 . User circuitry  425  determines candidate roaming access nodes from roaming 5GNR gNodeB  434  and 5G RAT node  435  based on the signal strengths. Typically, user circuitry  425  selects roaming access nodes that have a received signal strength strong enough to support wireless data services as candidate roaming access nodes. User circuitry  425  determines a network performance differential between home 5GNR gNodeB  433  and roaming 5GNR gNodeB  434  and a network performance differential between 5GNR gNodeB  433  and roaming 5G RAT node  435 . For example, the network performance differentials may indicate differences between home 5GNR gNodeB  433  and roaming nodes  434 - 435  in network error rate, throughput, band fading, intermodulation, interference, and/or other network performance indicators. User circuitry  425  ranks the candidate roaming access nodes by network performance differential. Typically, user circuitry  425  ranks candidate roaming access nodes with a larger performance differential high than candidate roaming access nodes with a smaller performance differential. 
     When at least one of the network performance differentials exceed a performance differential threshold, user circuitry  425  generates a handover request to attach to the candidate roaming access node with the largest performance differential. In some examples, user circuitry  425  may generate a handover request in response to other triggering events in addition to the exceeded performance differential threshold. For example, user circuitry  425  may determine that a GBR application is active, a UE WiFi hotspot capability is active, and/or other triggering events are active and responsively generate a handover request when the performance differentials exceed a performance differential threshold. 
     User circuitry  425  transfers the handover request to attach to the selected candidate roaming access node to home 5GNR gNodeB  433  over 5GNR radio  423 . Home 5GNR gNodeB  433  transfers the handover request to home 5GC  443 . Home 5GC  443  routes the handover request to the roaming 5GC associated with the selected candidate roaming access node. For example, if the handover request indicates the selected candidate roaming access node is roaming 5G RAT node  435 , then home 5GC  443  routes the handover request to roaming 5GC  445 . The selected roaming 5GC accepts the request. Home 5GC  443  directs home 5GNR gNodeB  433  to notify user circuitry  425 . Home 5GNR gNodeB  433  transfers a notification to 5GNR radio  423  that indicates that the handover request has been accepted. 5GNR radio  423  transfers the notification to user circuitry  425 . 
     User circuitry  425  directs 5GNR radio  423  to detach from home 5GNR gNodeB  433  and directs 5GNR radio  423  or 5G RAT radio  424  to attach to the selected candidate roaming access node of roaming access nodes  431 - 432 . User circuitry  425  exchanges attachment signaling with the selected candidate roaming access node over radio. User circuitry  425  exchanges user data with the selected candidate roaming access node over the radio. 
     In some examples, user circuitry  425  stores a PLMN list of PLMNs that 5G UE  411  can attach to and receive wireless communications service. The PLMN list may indicate network performance information for each of the PLMNs and the access nodes associated with the PLMNs. For example, the performance information may indicate network throughput, network error rate, band fading, interference level, and/or other performance information associated with the PLMNs. The PLMN list may further indicate performance differential thresholds for each of the available PLMNs. User circuitry  425  updates the performance information in the PLMN list when user circuitry  425  receives new PLMN data. User circuitry  425  may receive new PLMN data over System Information Blocks (SIBs) broadcast by home 5GNR gNodeB  433 , roaming 5GNR gNodeBs  434 , and roaming 5G RAT node  435 . User circuitry  425  may determine new PLMN data when UE  411  is attached to one of the PLMNs. For example, user circuitry  425  may measure network throughput for home 5GNR gNodeB  433  and store the network throughput for the PLMN of home 5GNR gNodeB  433  in the PLMN list. User circuitry  425  may utilize the stored performance information from the PLMN list to determine the network performance differentials. For example, home 5GNR eNodeB  433  may not be able to provide network performance information for each of the available PLMNs and user circuitry  425  may instead use the PLMN list to determine the performance information. In some examples, user circuitry  425  comprises a Subscriber Identity Module (SIM) and the SIM of user circuitry  425  stores the PLMN list. 
     Advantageously, 5GNR/LTE UE  410  generates a handover request to attach to a roaming access node in response to a performance differential between the home and roaming access nodes. Moreover, 5G UE  411  generates a handover request to attach to a roaming access node in response to a performance differential between the home and roaming access node. 
       FIG.  5    illustrates 5GNR/LTE UE  410  that generates a handover request based on network performance differentials. 5GNR/LTE UE  410  is an example of UE  101 , although UE  101  may differ. UE  410  comprises LTE radio  420 , 5GNR radio  421 , and user circuitry  422  that are coupled over bus circuitry. Radios  420 - 421  comprise antennas, amplifiers, filters, modulation, analog-to-digital interfaces, DSP, and memory that are coupled over bus circuitry. User circuitry  422  comprises user interfaces, CPU, and memory that are coupled over bus circuitry. 
     The antennas in radios  420  and  421  are wirelessly coupled to home LTE eNodeB  430 , roaming 5GNR gNodeB  431 , and roaming 5GNR gNodeB  432 . The user interfaces in user circuitry  422  comprise graphic displays, machine controllers, sensors, cameras, transceivers, and/or some other user components. The memory in user circuitry  422  stores an operating system, user applications (USER), and network applications like Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), Media Access Control (MAC), and Physical Layer (PHY). The CPU in user circuitry  422  executes the operating system and the user applications to generate and consume user data. The CPU in user circuitry  422  executes the operating system and the network applications to wirelessly exchange corresponding signaling and data with home LTE eNodeB  430 , roaming 5GNR gNodeB  431 , and roaming 5GNR gNodeB  432 . 
     In operation, the LTE RRC in 5GNR/LTE UE  410  wirelessly attaches to home LTE eNodeB  430  over antennas in LTE radio  420 . The LTE RRC in UE  410  generates UL LTE signaling and UL LTE data. The UL signaling indicates UE capabilities for different PLMNs of UE  410 . The LTE network applications in UE  410  process the UL LTE signaling and the UL LTE data to generate corresponding UL LTE symbols that carry the UL LTE signaling and UL LTE data. The LTE DSP in LTE radio  420  processes the UL LTE symbols to generate corresponding digital signals for the analog-to-digital interfaces. The analog-to-digital interfaces convert the digital UL signals into analog UL signals for modulation. Modulation up-converts the UL signals to their carrier frequency. The amplifiers boost the modulated UL signals for the filters which attenuate unwanted out-of-band energy. The filters transfer the filtered UL signals through duplexers to the antennas. The electrical UL signals drive the antennas to emit corresponding wireless LTE signals that transport the UL LTE signaling (indicating the UE capabilities for the different PLMNs) and UL LTE data for UE  410  to LTE eNodeB  430 . 
     The LTE antennas in LTE radio  420  receive wireless DL signals having DL LTE signaling and DL LTE data and transfer corresponding DL signals through duplexers to the amplifiers. The amplifiers boost the received DL signals for filters which attenuate unwanted energy. Demodulators down-convert the DL signals from their carrier frequency. The analog/digital interfaces convert the analog DL signals into digital DL signals for the DSP. The DSP recovers DL LTE symbols from the DL digital signals. The CPUs execute the network applications to process the DL LTE symbols and recover the DL LTE signaling and DL LTE data. The DL LTE signaling indicates performance metrics for home LTE eNodeB  430 , roaming 5GNR gNodeB  431 , and roaming 5GNR gNodeB  432 , APNs, QCIs, and network addresses from Home LTE eNodeB  430 . 
     The LTE RRC in user circuitry  422  drives the 5GNR RRC to direct the 5GNR PHY to measure signal strengths for roaming 5GNR gNodeBs  431 - 432 . The 5GNR PHY measures the signal strength for roaming 5GNR gNodeBs  431  and the signal strength for roaming 5GNR gNodeB  432 . The 5GNR PHY transfers the received signal strengths for roaming 5GNR gNodeBs  431 - 432  to the LTE RRC. The LTE RRC determines candidate roaming access nodes based on the received signal strengths of roaming 5GNR gNodeBs  431 - 432 . For example, the LTE RRC may implement a data structure to compare the received signal strengths to a signal strength threshold to determine if roaming 5GNR gNodeBs  431 - 432  comprise candidate roaming access nodes. The LTE RRC determines network performance differentials between home LTE eNodeB  430  and roaming 5GNR gNodeBs  431 - 432 . The network performance differentials indicate differences in performance between home LTE eNodeB  430  and roaming 5GNR gNodeBs  431 - 432 . The network performance differentials may indicate differences in network error rate, throughput, band fading, intermodulation, interference, and/or other network performance indicators. For example, the LTE RRC may determine the network throughput for home LTE eNodeB  430 , the network throughput for roaming 5GNR gNodeB  431 , and the difference in network throughput between home LTE eNodeB  430  and roaming 5GNR gNodeB  431  to determine the network performance differential for roaming 5GNR gNodeB  431 . The LTE RRC ranks the candidate roaming access nodes by network performance differential. The LTE RRC ranks candidate roaming access nodes with a larger performance differential higher than candidate roaming access nodes with a smaller performance differential. 
     The LTE RRC determines a performance differential threshold for the candidate roaming access nodes. In some examples, the LTE RRC determines individual performance differential thresholds for each candidate roaming access nodes. When at least one of the network performance differentials exceed the performance differential threshold, the LTE RRC generates a handover request to attach to the candidate roaming access node with the largest performance differential. In some examples, the LTE RRC may generate a handover request in response to other triggering events in addition to the exceeded performance differential threshold. The triggering events may comprise a GBR application, a UE WiFi hotspot, premium UE user application, or some other type of triggering event. For example, the LTE RRC may determine that a GBR application is active and responsively generate a handover request when the performance differentials exceed the performance differential threshold and the GBR application is active. 
     The LTE RRC directs the LTE PHY to transfer the handover request to home LTE eNodeB  430  over LTE radio  420  to attach to the selected candidate roaming access node. The LTE RRC receives indication from home LTE eNodeB  430  that handover request has been accepted. The LTE RRC detaches from home LTE eNodeB  430  and directs the 5GNR RRC to attach to attach to the selected candidate roaming access node of roaming access nodes  431 - 432 . The 5GNR RRC exchanges attachment signaling with the selected candidate roaming access node over 5GNR radio  421 . The 5GNR RRC attaches to the selected candidate roaming access node. The 5GNR PDCP exchanges user data with the selected candidate roaming access node over 5GNR radio  421 . 
     In some examples, user circuitry  422  stores a PLMN list of PLMNs that UE  410  can attach to and receive wireless communications service. The PLMN list may indicate network performance information for each of the PLMNs and the access nodes associated with the PLMNs. For example, the performance information may indicate network throughput, network error rate, band fading, interference level, and/or other performance information associated with the PLMNs. The PLMN list may further indicate performance differential thresholds for each of the available PLMNs. The LTE RRC updates the performance information in the PLMN list when the LTE RRC receives new PLMN data. The LTE RRC may receive new PLMN data over System Information Blocks (SIBs) broadcast by home LTE eNodeB  430  and the 5GNR RRC may receive new PLMN data over SIBs broadcast by roaming 5GNR gNodeBs  431 - 432 . The RRCs may determine new PLMN data when UE  410  is attached to one of the PLMNs. For example, the LTE RRC may measure network throughput for home LTE eNodeB  430  and store the network throughput for the PLMN of LTE eNodeB  430  in the PLMN list. The RRCs may utilize the stored performance information from the PLMN list to determine the network performance differentials. For example, home LTE eNodeB  430  may not be able to provide network performance information for each of the available PLMNs and LTE RRC may instead retrieve the performance information from the PLMN list. In some examples, user circuitry  422  comprises a Subscriber Identity Module (SIM) and the SIM of user circuitry  422  stores the PLMN list. 
       FIG.  6    illustrates 5G UE  411  that generates a handover request based on network performance differentials. 5G UE  411  is an example of UE  101 , although UE  101  may differ. UE  411  comprises 5GNR radio  423 , 5GNR RAT radio  424 , and user circuitry  425  that are coupled over bus circuitry. Radios  423 - 424  comprise antennas, amplifiers, filters, modulation, analog-to-digital interfaces, DSP, and memory that are coupled over bus circuitry. User circuitry  425  comprises user interfaces, CPU, and memory that are coupled over bus circuitry. The antennas in 5GNR radio  423  are wirelessly coupled to home 5GNR gNodeB  433  and roaming 5GNR gNodeB  434 . The antennas in 5GNR RAT radio  424  are wirelessly coupled to roaming 5G RAT node  435 . The user interfaces in user circuitry  425  comprise graphic displays, machine controllers, sensors, cameras, transceivers, and/or some other user components. The memory in user circuitry  425  stores an operating system (OS), user applications (USER), and network applications (RRC, SDAP, PDCP, RLC, MAC, and PHY). The CPU in user circuitry  425  executes the operating system and the user applications to generate and consume user data. The CPU in user circuitry  425  executes the operating system and the network applications to wirelessly exchange corresponding signaling and data with home 5GNR gNodeB  433  and roaming 5GNR gNodeB  434  over 5GNR radio  423 , with roaming 5G RAT node  435  over 5G RAT radio  424 . 
     In operation, the 5GNR RRC in UE  411  wirelessly attaches to home 5GNR gNodeB  433  over antennas in 5GNR radio  423 . The 5GNR RRC generates 5GNR signals that transport UL 5GNR signaling and UL 5GNR data. The 5GNR signaling indicates UE capabilities for different PLMNs. The 5GNR network applications in UE  411  process the UL 5GNR signaling and the UL 5GNR data to generate corresponding UL 5GNR symbols that carry the UL 5GNR signaling and UL 5GNR data. The 5GNR DSP in 5GNR radio  423  processes the UL 5GNR symbols to generate corresponding digital signals for the analog-to-digital interfaces. The analog-to-digital interfaces convert the digital UL signals into analog UL signals for modulation. Modulation up-converts the UL signals to their carrier frequency. The amplifiers boost the modulated UL signals for the filters which attenuate unwanted out-of-band energy. The filters transfer the filtered UL signals through duplexers to the antennas. The electrical UL signals drive the antennas to emit corresponding wireless 5GNR signals that transport the UL 5GNR signaling (indicating the UE capabilities for the different PLMNs) and UL 5GNR data for UE  411  to home 5GNR gNodeB  433 . 
     The 5GNR antennas 5GNR radio  423  receive wireless DL signals that have DL 5GNR signaling, DL 5GNR data, and a 5GNR measurement object and transfer corresponding DL signals through duplexers to the amplifiers. The amplifiers boost the received DL signals for filters which attenuate unwanted energy. Demodulators down-convert the DL signals from their carrier frequency. The analog/digital interfaces convert the analog DL signals into digital DL signals for the DSP. The DSP recovers DL 5GNR symbols from the DL digital signals. The CPUs in UE  411  execute the network applications to process the DL 5GNR symbols and recover the DL 5GNR signaling having the network performance information for home 5GNR gNodeB  433 , roaming 5GNR gNodeB  434 , and roaming 5G RAT node  435 , QoS levels, network addresses, and the like and the DL 5GNR data. 
     The 5GNR RRC directs the 5GNR PHY to measure signal strength for roaming 5GNR gNodeB  434 . The 5GNR RRC directs the 5G RAT RRC to drive the 5G RAT PHY to measure signal strength for roaming 5G RAT node  435 . The 5GNR PHY and the 5G RAT PHY measure the signal strengths and transfer the signal strengths to the 5GNR RRC. The 5GNR RRC determines candidate roaming access nodes from roaming 5GNR gNodeB  434  and 5G RAT node  435  based on the signal strengths. For example, the 5GNR RRC may implement a data structure to compare the received signal strengths to a signal strength threshold to determine if roaming access nodes  434 - 435  comprise candidate roaming access nodes. The 5GNR RRC determines a network performance differential between home 5GNR gNodeB  433  and roaming 5GNR gNodeB  434  and a network performance differential between home 5GNR gNodeB  433  and roaming 5G RAT node  435 . The network performance differentials indicate differences in performance between home 5GNR gNodeB  433  and roaming nodes  434 - 435 . The network performance differentials may indicate differences in network error rate, throughput, band fading, intermodulation, interference, and/or other network performance indicators. For example, the 5GNR RRC may determine the network throughput for home 5GNR gNodeB  433 , the network throughput for roaming 5G RAT node  435 , and the difference in network throughput between home 5GNR gNodeB  433  and roaming 5G RAT node  435  to determine the network performance differential for roaming 5G node  435 . The 5GNR RRC ranks the candidate roaming access nodes by network performance differential. Typically, the 5GNR RRC ranks the candidate roaming access nodes with a larger performance differential high than candidate roaming access nodes with a smaller performance differential. 
     The 5GNR RRC determines a network performance differential threshold for the candidate roaming access nodes. In some examples, the 5GNR RRC determines individual performance differential thresholds for each of the candidate roaming access nodes. When at least one of the network performance differentials exceed the performance differential threshold, the 5GNR RRC generates a handover request to attach to the candidate roaming access node with the largest performance differential. In some examples, the 5GNR RRC may generate a handover request in response to other triggering events in addition to the exceeded performance differential threshold. The triggering events may comprise a GBR application, a UE WiFi hotspot, a premium UE user application, or some other type of triggering event. For example, the LTE RRC may determine that a UE WiFi hotspot is active and responsively generate a handover request when the performance differentials exceed the performance differential threshold, and the UE WiFi hotspot is active. 
     The 5GNR RRC transfers the handover request to attach to the selected candidate roaming access node to home 5GNR gNodeB  433 . The 5GNR RRC receives a notification that the handover request is accepted from home 5GNR gNodeB  423 . The 5GNR RRC detaches from home 5GNR gNodeB  433 . The 5GNR RRC attaches to the selected candidate roaming access node of roaming access nodes  434 - 435 . In some examples, the 5GNR RRC drives the 5G RAT RRC to attach when the selected candidate roaming access node is roaming 5G RAT node  435 . The corresponding RRCs in UE  411  exchange attachment signaling with the selected candidate roaming access node over radio. The corresponding SDAPs exchange user data with the selected candidate roaming access node over the corresponding radios. 
     In some examples, user circuitry  425  stores a PLMN list of PLMNs that UE  411  can attach to and receive wireless communications service. The PLMN list may indicate network performance information for each of the PLMNs and the access nodes associated with the PLMNs. For example, the performance information may indicate network throughput, network error rate, band fading, interference level, and/or other performance information associated with the PLMNs. The PLMN list may further indicate performance differential thresholds for each of the available PLMNs. The 5GNR RRC updates the performance information in the PLMN list when the 5GNR RRC receives new PLMN data. The 5GNR RRC may receive new PLMN data over SIBs broadcast by home 5GNR gNodeB  433  and roaming 5NGR gNodeB  434  and the 5G RAT RRC may receive new PLMN data over SIBs broadcast by roaming 5G RAT node  435 . The RRCs may determine new PLMN data when UE  411  is attached to one of the PLMNs. For example, the 5GNR RRC may measure network throughput for home 5GNR gNodeB  433  and store the network throughput for the PLMN of 5GNR gNodeB  433  in the PLMN list. The RRCs may utilize the stored performance information from the PLMN list to determine the network performance differentials. For example, home 5GNR gNodeB  433  may not be able to provide network performance information for each of the available PLMNs and LTE RRC may instead retrieve the performance information from the PLMN list. In some examples, user circuitry  425  comprises a Subscriber Identity Module (SIM) and the SIM of user circuitry  425  stores the PLMN list. 
       FIG.  7    illustrates home LTE eNodeB  430  to hand over wireless UE  410  based network performance. Home LTE eNodeB  430  is an example of home access node  140 , although home access node  140  may differ. Home LTE eNodeB  430  comprises LTE radio  701  and LTE Baseband Unit (BBU)  702 . Radio  701  comprises antennas, amplifiers, filters, modulation, analog-to-digital interfaces, DSP, memory, and transceivers (XCVR) that are coupled over bus circuitry. LTE BBU  702  comprises memory, CPU, and transceivers that are coupled over bus circuitry. The memory in LTE BBU  702  stores operating systems (OS) and network applications like Physical Layer (PHY), Media Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Radio Resource Control (RRC). The CPU in LTE BBU  702  executes the operating systems, PHYs, MACs, RLCs, PDCPs, and RRCs to exchange network signaling and user data between UE  410  and home EPC  440 . UE  410  is wirelessly coupled to the antennas in LTE radio  701  over an LTE link. The transceiver in LTE radio  701  is coupled to a transceiver in LTE BBU  702  over Common Public Radio Interface (CPRI) links. A transceiver in LTE BBU  702  is coupled to home EPC  440  over backhaul links. 
     RRC functions comprise authentication, security, handover control, status reporting, Quality-of-Service (QoS), network broadcasts and pages, and network selection. PDCP functions comprise LTE/5GNR allocations, security ciphering, header compression and decompression, sequence numbering and re-sequencing, de-duplication. RLC functions comprise Automatic Repeat Request (ARQ), sequence numbering and resequencing, segmentation and resegmentation. MAC functions comprise buffer status, power control, channel quality, Hybrid Automatic Repeat Request (HARM), user identification, random access, user scheduling, and QoS. PHY functions comprise packet formation/deformation, windowing/de-windowing, guard-insertion/guard-deletion, parsing/de-parsing, control insertion/removal, interleaving/de-interleaving, Forward Error Correction (FEC) encoding/decoding, rate matching/de-matching, scrambling/descrambling, modulation mapping/de-mapping, channel estimation/equalization, Fast Fourier Transforms (FFTs)/Inverse FFTs (IFFTs), channel coding/decoding, layer mapping/de-mapping, precoding, Discrete Fourier Transforms (DFTs)/Inverse DFTs (IDFTs), and Resource Element (RE) mapping/de-mapping. 
     In operation, UE  410  wirelessly attaches to LTE antennas in LTE radio  701 . The LTE antennas in LTE radio  701  receive wireless LTE signals from UE  410  that transport Uplink (UL) LTE signaling, UL LTE data. The UL signaling indicates UE capabilities of UE  410  for different PLMNs. The antennas transfer corresponding electrical UL signals through duplexers to the amplifiers. The amplifiers boost the received UL signals for filters which attenuate unwanted energy. Demodulators down-convert the UL signals from their carrier frequency. The analog/digital interfaces convert the analog UL signals into digital UL signals for the DSP. The DSP recovers UL LTE symbols from the UL digital signals. The CPUs execute the network applications to process the UL LTE symbols and recover the UL LTE signaling and the UL LTE data. The RRC processes the UL LTE signaling and Downlink (DL) S1-MME signaling to generate new UL S1-MME signaling and new DL LTE signaling. The RRC transfers the new UL S1-MME signaling, including the capabilities of UE  410 , to home EPC  440  over the backhaul links. Home EPC  440  authenticates and authorizes service for UE  410 . In response to the UE capabilities, Home EPC  440  retrieves network performance information for roaming 5GCs  441 - 442  from roaming 5GCs  441 - 442 . In LTE BBU  702 , the LTE RRC receives the DL S1-MME signaling that indicates the performance information for roaming 5GCs  441 - 442  and performance information for home EPC  440 . The LTE PDCP transfers the UL LTE data to home EPC  440  over the backhaul links. The LTE PDCP receives DL LTE data from EPC  440 . 
     The LTE network applications process the new DL LTE signaling and the DL LTE data to generate corresponding DL LTE symbols that carry the DL LTE signaling, DL LTE data, and the performance information. In LTE radio  701 , the DSP processes the DL LTE symbols to generate corresponding digital signals for the analog-to-digital interfaces. The analog-to-digital interfaces convert the digital DL signals into analog DL signals for modulation. Modulation up-converts the DL signals to their carrier frequency. The amplifiers boost the modulated DL signals for the filters which attenuate unwanted out-of-band energy. The filters transfer the filtered DL signals through duplexers to the antennas. The electrical DL signals drive the antennas to emit corresponding wireless LTE signals that transport the DL LTE signaling, DL LTE data, and performance information to UE  410 . 
     LTE radio  701  receives a handover request from UE  410  to attach to a roaming access node of roaming 5GNR gNodeBs  431 - 432 . LTE radio  701  transfers the handover request to the LTE RRC in LTE BBU  702  over the CPRI links. The LTE RRC transfers the handover request to home EPC  440  over the backhaul links. Home EPC  440  routes the handover request to the roaming 5GC associated with the selected candidate roaming access node. For example, if the handover request indicates the selected candidate roaming access node is roaming 5GNR gNodeB  431 , then home EPC  440  routes the handover request to roaming 5GC  441 . The selected roaming 5GC accepts the request. Home EPC  440  directs home the LTE RRC in BBU  702  to notify UE  410 . The LTE RRC transfers a notification to UE  410  over LTE radio  701  that indicates that the handover request has been accepted. UE  410  detaches from home LTE eNodeB  430  and attaches to the selected candidate roaming access node of roaming 5GNR gNodeBs  431 - 432 . UE  410  exchanges attachment signaling with the selected candidate roaming access node. UE  410  exchanges user data with the selected candidate roaming access node over the radio. 
       FIG.  8    illustrates home 5GNR gNodeB  433  to hand over 5G UE  411  based on network performance. Home 5GNR gNodeB  433  is an example of home access node  140 , although home access node  140  may differ. Home 5GNR gNodeB  433  comprises 5GNR radio  801  and 5GNR BBU  802 . 5GNR radio  801  comprises antennas, amplifiers, filters, modulation, analog-to-digital interfaces, DSP, memory, and transceivers that are coupled over bus circuitry. UE  411  is wirelessly coupled to the antennas in 5GNR radio  801  over a 5GNR link. The transceiver in 5GNR radio  801  is coupled to a transceiver in 5GNR BBU  802  over CPRI links. A transceiver in 5GNR BBU  802  is coupled to home 5GC over backhaul links. 5GNR BBU  802  comprises memories, CPUs, and transceivers that are coupled over bus circuitry. The memory in 5GNR BBU  803  stores operating systems (OS) and network applications like PHY, MAC, RLC, PDCP, RRC, and Service Data Adaptation Protocol (SDAP). The CPU in 5GNR BBU  803  executes the operating systems, PHYs, MACs, RLCs, PDCPs, SDAPs, and RRCs to exchange network signaling and user data with UE  411  and with home 5GC  443 . 
     RRC functions comprise authentication, security, handover control, status reporting, QoS, network broadcasts and pages, and network selection. SDAP functions comprise QoS marking and flow control. PDCP functions comprise LTE/5GNR allocations, security ciphering, header compression and decompression, sequence numbering and re-sequencing, and de-duplication. RLC functions comprise ARQ, sequence numbering and resequencing, and segmentation and resegmentation. MAC functions comprise buffer status, power control, channel quality, HARQ, user identification, random access, user scheduling, and QoS. PHY functions comprise packet formation/deformation, windowing/de-windowing, guard-insertion/guard-deletion, parsing/de-parsing, control insertion/removal, interleaving/de-interleaving, FEC encoding/decoding, rate matching/de-matching, scrambling/descrambling, modulation mapping/de-mapping, channel estimation/equalization, FFTs/IFFTs, channel coding/decoding, layer mapping/de-mapping, precoding, DFTs/IDFTs, and RE mapping/de-mapping. 
     In operation, 5G UE  411  wirelessly attaches to 5GNR radio  801 . In 5GNR radio  801 , the antennas receive wireless 5GNR signals from 5G UE  411  that transport UL 5GNR signaling and UL 5GNR data. The 5G UL signaling from UE  411  indicates UE capabilities of UE  411  for different PLMNs. The antennas transfer corresponding electrical UL signals through duplexers to the amplifiers. The amplifiers boost the received UL signals for filters which attenuate unwanted energy. Demodulators down-convert the UL signals from their carrier frequency. The analog/digital interfaces convert the analog UL signals into digital UL signals for the DSP. The DSP recovers UL 5GNR symbols from the UL digital signals. The CPUs execute the network applications to process the UL 5GNR symbols and recover the UL 5GNR signaling and the UL 5GNR data. The 5GNR RRC in 5GNR BBU  802  processes the UL 5GNR signaling and DL N2 signaling from home 5GC  443  to generate new UL N2 signaling that indicates the UE capabilities for the different PLMNs and new DL 5GNR signaling. The 5GNR RRC transfers the new UL N2 signaling that indicates the UE capabilities for different PLMNs to home 5GC  443 . The 5GNR SDAP in 5GNR BBU  802  transfers the UL 5GNR data to home 5GC  443  over backhaul links. In response to the UE capabilities, home 5GC  443  retrieves network performance information for roaming 5GCs  444 - 445  from home 5GCs  444 - 445 . 
     In 5GNR BBU  802 , the 5GNR RRC receives the DL N2 signaling from home 5GC  443  that indicates network performance information for home 5GC  443  and for roaming 5GCs  444 - 445 . The 5GNR SDAP receives DL 5GNR data from home 5GC  443 . The 5GNR network applications process the new DL 5GNR signaling and the DL 5GNR data to generate corresponding DL 5GNR symbols that carry the DL 5GNR signaling and DL 5GNR data. In 5GNR radio  801 , the DSP processes the DL 5GNR symbols to generate corresponding digital signals for the analog-to-digital interfaces. The analog-to-digital interfaces convert the digital DL signals into analog DL signals for modulation. Modulation up-converts the DL signals to their carrier frequency. The amplifiers boost the modulated DL signals for the filters which attenuate unwanted out-of-band energy. The filters transfer the filtered DL signals through duplexers to the antennas. The electrical DL signals drive the antennas to emit corresponding wireless 5GNR signals that transport the DL 5GNR signaling that indicates the network performance information and the DL 5GNR data to 5G UE  411 . 
     5GNR radio  801  receives a handover request from UE  411  to attach to a roaming access node of roaming 5GNR gNodeBs  434  and 5G RAT node  435 . 5GNR radio  801  transfers the handover request to the 5GNR RRC in 5GNR BBU  802  over the CPRI links. The 5GNR RRC transfers the handover request to home 5GC  443  over the backhaul links. Home 5GC  443  routes the handover request to the roaming 5GC associated with the selected candidate roaming access node. For example, if the handover request indicates the selected candidate roaming access node is roaming 5GNR gNodeB  434 , then home 5GC  443  routes the handover request to roaming 5GC  444 . The selected roaming 5GC accepts the request. Home 5GC  443  directs home the 5GNR RRC in BBU  802  to notify UE  411 . The 5GNR RRC transfers a notification to UE  411  over 5GNR radio  801  that indicates that the handover request has been accepted. UE  411  detaches from home 5GNR gNodeB  433  and attaches to the selected candidate roaming access node of roaming 5GNR gNodeB  434  and 5G RAT node  435 . UE  411  exchanges attachment signaling with the selected candidate roaming access node. UE  411  exchanges user data with the selected candidate roaming access node over the radio. 
       FIG.  9    illustrates an exemplary operation of 5GNR/LTE UE  410 , Home LTE eNodeB  430 , and home EPC  440  to hand over 5GNR/LTE UE  410  based on network performance. In 5GNR/LTE UE  410 , a user application requests data communication, and the LTE RRC in UE  410  attaches to the LTE RRC in home LTE eNodeB  430  over the LTE PDCPs, RLCs, MACs, and PHYs. The LTE RRC in UE  410  indicates UE capabilities of UE  410  for different PLMNs to the LTE RRC in home LTE eNodeB  430 . The LTE RRC in home LTE eNodeB  430  transfers S1-MME signaling to home EPC  440  that requests data services and indicates the UE capabilities of UE  410 . 
     EPC  440  authenticates and authorizes UE  410  for wireless data services represented by APNs. In response to the authorization and the UE capabilities for different PLMNs, home EPC  440  retrieves network performance information for roaming 5GCs  441 - 442  from roaming 5GCs  441 - 442 . Home EPC  440  selects QCIs and network addresses for UE  410  based on the APNs. Home EPC  440  transfers the APNs, QCIs, network address, performance information for home EPC  440 , and the performance information roaming 5GCs  441 - 442  to the LTE RRC in home LTE eNodeB  430 . The LTE RRC in home LTE eNodeB  430  transfers the APNs, QCIs, network address, and the performance information to the LTE RRC in UE  410  over the PDCPs, RLCs, MACs, and PHYs. EPC  440  exchanges the user data with the PDCP in home LTE eNodeB  430 . The PDCP in home LTE eNodeB  430  exchanges the user data with the PDCP in UE  410  over the RLCs, MACs, and PHYs. 
     The LTE RRC in UE  410  directs the 5GNR RRC in UE  410  to drive the 5GNR PHY to measure signal strength for roaming 5GNR gNodeBs  431  and signal strength for roaming 5GNR gNodeB  432 . The 5GNR PHY measures the signal strengths and transfers the received signal strengths for roaming 5GNR gNodeBs  431 - 432  to the LTE RRC. The LTE RRC determines candidate roaming access nodes based on the signal strengths of roaming 5GNR gNodeBs  431 - 432 . For example, the LTE RRC may select roaming access nodes with high received signal strength as candidate roaming access nodes. The LTE RRC determines network performance differentials between home LTE eNodeB  430  and roaming 5GNR gNodeBs  431 - 432  based on the network performance information. For example, the LTE RRC may determine the amount interference for home LTE eNodeB  430  and for roaming 5GNR gNodeBs  431 - 432  the difference between the amounts of interference to determine the network performance differentials. The LTE RRC ranks the candidate roaming access nodes based on network performance differential. Typically, the LTE RRC ranks candidate roaming access nodes with a larger performance differential higher than candidate roaming access nodes with a smaller performance differential. 
     When the network performance differentials exceed a performance differential threshold, the LTE RRC generates a handover request to attach to the candidate roaming access node with the largest performance differential. The LTE RRC transfers the handover request to attach to the selected candidate roaming access node to the LTE RRC in home LTE eNodeB  430  over the PDCPs, RLCs, MACs, and PHYs. The LTE RRC in LTE eNodeB  430  transfers the handover request to home EPC  440 . Home EPC  440  routes the handover request to the roaming 5GC associated with the selected candidate roaming access node. For example, if the handover request indicates the selected candidate roaming access node is roaming 5GNR gNodeB  431 , then home EPC  440  routes the handover request to roaming 5GC  441 . The selected roaming 5GC accepts the request. Home EPC  440  directs the LTE RRC in home LTE eNodeB  430  to notify UE  410 . The LTE RRC in home LTE eNodeB  430  transfers a notification that indicates the accepted request to the LTE RRC in UE  410  over the PDCPs, RLCs, MACs, and PHYs. 
     The LTE RRC in UE  410  receives the notification and responsively detaches from the LTE RRC in home LTE eNodeB  430 . The LTE RRC in UE  410  directs the 5GNR RRC in UE  410  to attach to the 5GRN RRC in the selected candidate roaming access node of roaming 5GNR gNodeBs  431 - 432 . The 5GNR RRC in UE  410  exchanges attachment signaling with the 5GNR RRC in the selected candidate roaming access node of roaming 5GNR gNodeBs  431 - 432  over the SDAPs, PDCPs, RLCs, MACs, and PHYs. The 5GNR RRC attaches to the selected candidate roaming access node. The 5GNR SDAP exchanges user data with the 5GNR SDAP in the selected candidate roaming access node over the PDCPs, RLCs, MACs, and PHYs. 
       FIG.  10    illustrates an exemplary operation of 5G UE  411 , home 5GNR gNodeB  433 , and home 5GC to hand over UE  411  based on network performance. In 5G UE  411 , a user application requests data communication, and the 5GNR RRC in UE  411  attaches to the 5GNR RRC in home 5GNR gNodeB  433  over the 5GNR SDAPs, PDCPs, RLCs, MACs, and PHYs. The 5GNR RRC in UE  411  indicates UE capabilities of UE  411  for different PLMNs to the 5GNR RRC in home 5GNR gNodeB  433 . The 5GNR RRC in home 5GNR gNodeB  433  sends a request for data services for 5G UE  411  in N2 signaling to home 5GC  443  over the backhaul links. Home 5GC  443  authenticates and authorizes 5G UE  411  for data services. In response the UE capabilities of UE  410 , home 5GC  410  requests performance information for roaming 5GCs  444 - 445  from the roaming 5GCs. Home 5GC  443  transfers quality-of-service metrics, network addressing, network performance information for home 5GC  443 , and network performance information for 5GCs  444 - 445  to the 5GNR RRC in home 5GNR gNodeB  433  in N2 signaling. The 5GNR RRC in home 5GNR gNodeB  433  transfers the selected APNs, QCIs, network addresses, and network performance information to the 5GNR RRC in UE  411  over the SDAPs, PDCPs, RLCs, MACs, and PHYs. 
     The 5GNR RRC in UE  411  directs the 5GNR PHY to measure signal strength for roaming 5GNR gNodeB  434 . The 5GNR RRC directs the 5G RAT RRC to drive the 5G RAT PHY to measure signal strength for roaming 5G RAT node  435 . The 5GNR PHY and the 5G RAT PHY measure the signal strengths and transfer the signal strengths to the 5GNR RRC. The 5GNR RRC determines candidate roaming access nodes from roaming 5GNR gNodeB  434  and 5G RAT node  435  based on the received signal strengths. The 5GNR RRC determines a network performance differential between home 5GNR gNodeB  433  and roaming 5GNR gNodeB  434  and a network performance differential between home 5GNR gNodeB  433  and roaming 5G RAT node  435 . The network performance differentials indicate differences in performance between home 5GNR gNodeB  433  and roaming nodes  434 - 435 . For example, the network performance differentials may indicate differences in network error rate, throughput, band fading, intermodulation, interference, and/or other network performance indicators. The 5GNR RRC ranks the candidate roaming access nodes by network performance differential. 
     When the network performance differentials exceed a performance differential threshold, the 5GNR RRC generates a handover request to attach to the candidate roaming access node with the largest performance differential. The 5GNR RRC transfers the handover request to attach to the selected candidate roaming access node to the 5GNR RRC in home 5GNR gNodeB  433  over the SDAPs, PDCPs, RLCs, MACs, and PHYs. The 5GNR RRC in home 5GNR gNodeB  433  transfers the handover request to home 5GC  443  in N2 signaling. Home 5GC  443  routes the request the roaming 5GC associated with the selected roaming access node. When the selected roaming access node accepts the request, home 5GC  443  directs the 5GNR RRC in home 5GNR gNodeB  433  to notify UE  411 . The 5GNR RRC transfers a notification indicating the accepted request to the 5GNR RRC in UE  411  over the SDAPs, PDCPs, RLCs, MACs, and PHYs. 
     The 5GNR RRC in UE  411  receives the notification that the handover request is accepted and detaches from the 5GNR RRC in home 5GNR gNodeB  433 . The 5GNR RRC attaches to the 5GNR RRC in the selected candidate roaming access node. In some examples, the 5GNR RRC drives the 5G RAT RRC to attach when the selected candidate roaming access node is roaming 5G RAT node  435 . The corresponding RRCs in UE  411  exchange attachment signaling with the corresponding RRCs in the selected candidate roaming access node. The corresponding SDAPs exchange user data with the corresponding SDAPs in the selected candidate roaming access node. 
     The wireless data network circuitry described above comprises computer hardware and software that form special-purpose network circuitry to hand over wireless UEs based network performance differentials. The computer hardware comprises processing circuitry like CPUs, DSPs, GPUs, transceivers, bus circuitry, and memory. To form these computer hardware structures, semiconductors like silicon or germanium are positively and negatively doped to form transistors. The doping comprises ions like boron or phosphorus that are embedded within the semiconductor material. The transistors and other electronic structures like capacitors and resistors are arranged and metallically connected within the semiconductor to form devices like logic circuitry and storage registers. The logic circuitry and storage registers are arranged to form larger structures like control units, logic units, and Random-Access Memory (RAM). In turn, the control units, logic units, and RAM are metallically connected to form CPUs, DSPs, GPUs, transceivers, bus circuitry, and memory. 
     In the computer hardware, the control units drive data between the RAM and the logic units, and the logic units operate on the data. The control units also drive interactions with external memory like flash drives, disk drives, and the like. The computer hardware executes machine-level software to control and move data by driving machine-level inputs like voltages and currents to the control units, logic units, and RAM. The machine-level software is typically compiled from higher-level software programs. The higher-level software programs comprise operating systems, utilities, user applications, and the like. Both the higher-level software programs and their compiled machine-level software are stored in memory and retrieved for compilation and execution. On power-up, the computer hardware automatically executes physically-embedded machine-level software that drives the compilation and execution of the other computer software components which then assert control. Due to this automated execution, the presence of the higher-level software in memory physically changes the structure of the computer hardware machines into special-purpose network circuitry to hand over wireless UEs based on network performance differentials. 
     The above description and associated figures teach the best mode of the invention. The following claims specify the scope of the invention. Note that some aspects of the best mode may not fall within the scope of the invention as specified by the claims. Those skilled in the art will appreciate that the features described above can be combined in various ways to form multiple variations of the invention. Thus, the invention is not limited to the specific embodiments described above, but only by the following claims and their equivalents.