Toward Massive-MIMO mmWave ISAC: An Open Framework for Scalable RF Sensing and Communications

Abstract

Next-generation wireless networks are expected to support sensing and communication through shared spectrum, hardware, and waveforms. However, most existing integrated sensing and communications (ISAC) demonstrations are built around a specific waveform, frequency band, or dedicated sensing platform, leaving a gap between standards compliant wireless infrastructure and practical sensing implementations across multiple frequency ranges. In this work, we present an open software-defined radio (SDR)-based experimental pathway for ISAC using existing fifth-generation New Radio (5G NR) infrastructure from sub-6 GHz to Frequency Range 2 (FR2) millimeter-wave (mmWave) operation.

We introduce PolyBase, which reuses a 3GPP-compliant 5G NR downlink waveform for long-range sensing using an OpenAirInterface (OAI) gNB and USRP X410. We also introduce an FR2 platform that extends the concept of 5G-infrastructure-enabled mmWave sensing to 27.5 GHz using USRP and Sivers mmWave front-ends, with channel state information reference signal (CSI-RS)-based channel measurements and over-the-air (OTA) sensing experiments. Experimental results demonstrate simultaneous detection of multiple outdoor targets with PolyBase and detection of a static human target in a controlled indoor FR2 environment after clutter subtraction. The resulting framework provides a practical roadmap for extending open, standards-based wireless infrastructure toward real-time, wideband, and next-generation ISAC systems.