As users move, the network must transfer the UE from one service cell to a neighboring destination cell with minimal disruption to ongoing data transmission and reception.
In current 5G deployments, the handover is typically initiated by the base station via a Radio Resource Control (RRC) message. Because the RRC operates at Layer 3 (L3), this procedure—commonly referred to as the L3 handover—introduces a brief service interruption. Even in well-optimized networks, this interruption is typically in the range of 50 to 90 milliseconds. While acceptable for many broadband use cases, this latency becomes a limitation for emerging time-critical communications (TCC) and extended reality (XR) services, where even brief interruptions can degrade the user experience.
To address this challenge, 3GPP Release 18 introduced Lower Layer Mobility (LTM), a new mobility mechanism that allows the network to trigger handover using Layer 2 signaling, based on Layer 1 measurements taken and reported by the UE. By leveraging lower layer information, the UE can synchronize in advance—both uplink and downlink—with a neighboring cell designated as an LTM candidate cell.
This proactive approach significantly accelerates the handover process, reducing execution time, signaling overhead, and service disruption. As a result, LTM delivers smoother mobility, meeting the stringent latency and reliability requirements of next-generation 5G applications and paving the way for advanced services in high-mobility environments and dense networks.
Through this initiative, Anritsu supports industry verification of LTM compliance and interoperability, helping to accelerate the commercial implementation of 3GPP version 18 features.
“Support for the bottom-layer enabled mobility (LTM) test cases of 3GPP NR Release 18 enables significantly faster and more reliable handover performance, which is critical for immersive, time-critical 5G services,” said Daizaburo Yokoo, general manager of Anritsu’s Mobile Solutions Division. “By enabling accurate verification of LTM functionality, Anritsu helps operators and device manufacturers reduce handover disruptions, decrease signaling overhead, and deliver a smoother user experience, even in high-mobility scenarios.”
“We are proud that this milestone will enable the industry to quickly and confidently deploy and validate advanced 5G mobility enhancements, such as Version 18 LTM,” he added. “This milestone supports the evolution of standalone 5G networks toward applications that demand ultra-low latency and high reliability.”.
*1: For submissions of NR LTM test cases to 3GPP RAN5 (Anritsu survey, April 2026)
Product Description ME7834NR 5G NR Mobile Device Test Platform The ME7834NR 5G NR Mobile Device Test Platform is registered as Test Platform 251 with both the GCF and PTCRB. This platform supports 3GPP-based Protocol Conformance Testing (PCT) and Carrier Acceptance Testing (CAT) for mobile devices incorporating multiple radio access technologies. It covers 5G NR in both standalone and non-standalone modes, along with LTE, LTE-Advanced, LTE-A Pro, W-CDMA, NTN, and now LTM. When combined with the MA8171A OTA RF camera and Anritsu RF converters, the ME7834NR supports testing in sub-6 GHz and millimeter wave (mmWave) 5G NR frequency bands.
