How to Improve Handover Performance in 5G Networks

For many service providers, handover performance remains an ever-changing yet critical component of commercial success. While simplistic in nature, the act of maintaining continuous connectivity is growing increasingly complicated as new devices and technologies are introduced.

To support an ever-evolving hybrid mobile environment using multiple radio access technologies (RATs), service providers need to understand the variety of scenarios that present themselves as subscribers use the network, including intra-RAT, inter-RAT, dual connectivity, and multiradio/dual-connectivity handovers.

Subscribers Demand and Utilize More in 5G and NETSCOUT Solutions Deliver

Adding more pressure to the task, today’s mobile networks handle more subscribers and more traffic than ever before, requiring service providers to prioritize planning and troubleshooting efforts around proactive identification, mitigation, and ideally, the prevention of handover failures.

Fortunately, comprehensive radio access network (RAN) visibility can assist operators in this endeavor. With tools such as NETSCOUT’s TrueCall, investigating the underlying cause of poor and failing handovers in the network is possible.

Whether the result of network congestion, interference, inaccurate configuration parameters, or equipment issues, service providers need a way to effectively visualize and investigate areas experiencing handover failures, with visibility to specific cells as well as to offending handset makes and models.

During NETSCOUT’s most recent Technology & User Summit, RAN Product Manager Wing Lo offered attendees a quick demonstration of how our customers benefit from real-time RAN visibility while investigating dropped calls occurring in a major metropolitan area. Via an interactive session, Lo showcased best practices including the use of event maps, heat maps, predefined reports, and advanced key performance indicators (KPIs).

Use a Combination of Event and Heat Maps to Characterize the Subscriber Experience

Whereas event maps offer a geographic representation of active call events, heat maps provide the much-needed density and intensity lens for more focused triage efforts.

As Lo explained during a demo pavilion talk, only heat maps can provide the user with on-screen, at-a-glance visualizations of handover attempts, failures, and failure rates for the distinct types of S1/N2 and X2/Xn handovers for intra- and inter-frequency scenarios.

By utilizing a heat map view of location and density performance information cataloged by geographic bin, service providers gain a better understanding not only of where handover traffic occurs but also of where the problems are happening. From this view, resolution teams are better equipped to apply meaningful filters for focused triage by specific groups of the actual calls represented on the map. In the case of our customers, these filters are often applied to select calls from a particular make and model of handset or to focus only on the calls using 5G non-standalone (NSA).

Add Clarity to Your Investigations with Predefined Reports and Advanced KPIs

In addition to heat maps, predefined report tables enable guided exploration of important network performance metrics and KPIs, including the makes and models of the devices experiencing dropped calls, degrading service quality, and increasing network congestion in a particular area. Here, solutions that offer a lengthy list of KPIs for calls in a selected area and during a specific time provide an advantage. Predefined KPIs accelerate the analysis of observed traffic with a concise overview of network health in terms of coverage, handovers, dropped calls, and many other indicators.

With TrueCall, this information appears in a call table where our customers have access to individual call details for more than 300 attributes including geographic location, start time, end time, the supporting cell for the call, signal quality, and number of handovers.

Like the heat maps, KPIs and call tables enable deeper investigations with subset cell selection and filtering of any call attribute.

In showcasing the product with customers, Lo walked TrueCall users through a typical use case where the “Query Filter” is used to easily select a subset of calls ending with poor signal strength, < -105 dBm, that were not able to handover within a specified time window for an identified geographic area.

Insist on Data That Represents the True Experience

For years, drive tests have been a mainstay for assessing coverage, handover performance, and other network metrics. And, although drive test calls are useful, they often are limited to a relatively small number of calls on open roads and within public areas. The majority of today’s traffic is generated by in-building users—locations not readily accessible with traditional drive test methods.

To address this limitation, NETSCOUT customers use TrueCall to gain insight into actual traffic distribution without bias or restrictions. By broadening their knowledge with a larger number of calls, they have access to conclusive KPIs and more intuitive heat maps—reducing the uncertainty and risks associated with smaller sample drive test calls.

Reduce Complexity with Tools That Can Address Handover Scenarios in Ever-evolving Networks

In further discussions, Lo outlined the following 5G handover use cases and how they are addressed with TrueCall.

• Cell connectivity. In 5G NSA call setups, user equipment (UE) will first set up an LTE call with an eNB before adding the 5G New Radio (NR) cell to the call for dual connectivity. With TrueCall, service providers can monitor the success or failure of the secondary 5G NR cell addition. Subsequently, if a 5G NR cell connectivity with the UE begins to deteriorate, TrueCall can identify the dropping of secondary NR cells.
• Configuration errors. In another scenario, if 5G NSA calls are not set up due to configuration errors involving Master eNB and Secondary gNB relationships, TrueCall can pinpoint when a 5G NSA-capable UE is receiving adequate 5G NR cell signal from measurement reports without subsequent 5G NR cell adds to the LTE call.
• Missing neighbor cells. In early 5G SA deployments, our experts see 5G NR handover issues caused by missing neighbors. For these discoveries, TrueCall can be used to find missing neighbor relationships by using filtering techniques. By focusing on 5G NR dropped calls with low reference signal received power (RSRP), service providers can highlight missing handovers in areas where strong neighbors are logged as present on measurement reports.

Discover More About TrueCall and 5G Network Optimization and Troubleshooting

For nearly a decade, TrueCall has served the needs of wireless service providers around the world with unmatched visibility for optimization and troubleshooting excellence. This intuitive platform, in combination with NETSCOUT’s frontline mobile network expertise, continues to guide the success of multigenerational core and radio access technology deployments.

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