Rohde & Schwarz and the China Mobile Research Institute showcased an AI user experience testbed at MWC Shanghai 2026, built around the CMX500 5G one-box signaling tester, to quantitatively assess generative AI performance on connected devices. The joint solution evaluates how network quality affects AI service responsiveness, as the adoption of large language model (LLM)-based services accelerates across smartphones, AI glasses and robots, while the industry still lacks mature metrics and standardised frameworks. In the demonstrated architecture, the LLM runs on a server or cloud, while the CMX500 creates a radio link to a smart terminal hosting a client test app, adjusting parameters like channel fading, latency, jitter, and RF impairments to emulate scenarios from ideal coverage to weak edge conditions. Users submit prompts and record indicators including Time to First Token (TTFT) and Tokens Per Second (TPS), with host PC software aggregating results for like-for-like comparisons. Liu Guangyi, Chief Expert of China Mobile, stated the testbed enables generative AI user experience testing across diverse wireless environments, with plans to expand test metrics and application scenarios for 6G-enabled AI technologies. Jin Hailiang, Senior Director at Rohde & Schwarz China, said the testbed sets an important benchmark for generative AI user experience testing.