Integrated Sensing and Communication

Description

Integrated Sensing and Communication (ISAC) is a paradigm in which a wireless network uses its radio interface not only to exchange data but also to sense the physical environment. In 3GPP, ISAC was first studied in Release 19, with normative work continuing in Release 20. The core idea is that the same OFDM waveforms, antennas, and spectrum used for 5G NR communication can also be exploited to detect targets (vehicles, pedestrians, drones, objects) and estimate their distance, velocity, angle, and other characteristics. This dual use of infrastructure promises new services such as high-accuracy positioning, environment mapping, intrusion detection, and automotive radar augmentation, without deploying separate radar systems.

From an architectural perspective, ISAC in 3GPP is primarily a radio access network (RAN) capability, though it has implications for the core network and services. The gNB (or a sensing-capable UE) transmits specially configured reference signals or uses existing communication signals. Echoes reflected from objects are received by the same or different nodes. The sensing receiver processes these echoes to extract target information. 3GPP has defined two main sensing modes: monostatic sensing, where the same node transmits and receives, and bistatic/multi-static sensing, where one node transmits and another receives. The latter is particularly useful for cooperative sensing and can improve coverage and accuracy. The network can also leverage UE-assisted sensing, where UEs perform measurements and report them.

Key technical enablers include the use of wide bandwidth (to achieve fine range resolution), large antenna arrays (for angular resolution), and advanced signal processing. 3GPP TR 38.901 provides channel models that include sensing-related aspects, while TS 22.870 defines service requirements, TS 26.858 covers media aspects (e.g., representing sensing data), and TR 28.893 addresses management and orchestration of ISAC. The sensing functionality is integrated into the NR frame structure, often using periodic or aperiodic sensing reference signals (e.g., based on CSI-RS or dedicated sensing signals). The network can configure sensing resources dynamically, balancing communication and sensing workloads. Interference management is crucial: sensing transmissions must not degrade communication quality, and communication traffic can be used as 'signals of opportunity' for passive sensing.

ISAC supports a wide range of use cases. In automotive and transport, it enables vehicle-to-everything (V2X) sensing, detecting pedestrians and obstacles beyond line-of-sight. In indoor environments, it supports presence detection, people counting, and gesture recognition. In public safety, it can detect intruders or monitor disaster areas. In industrial IoT, it can track assets and ensure worker safety. The accuracy and latency requirements vary; some services need sub-meter positioning and low latency, while others tolerate higher latency. 3GPP is defining sensing QoS parameters, such as detection probability, false alarm rate, and accuracy, to characterize sensing performance.

ISAC represents a convergence of communications and radar, leveraging the trend toward higher frequencies (mmWave, sub-THz), larger bandwidths, and massive MIMO. It is seen as a key feature of 5G-Advanced and 6G, where sensing becomes an inherent network service. 3GPP Release 19 studied the feasibility and defined initial specifications, while Release 20 is expected to refine and extend the framework, including support for new frequency bands and integration with core network services. ISAC also raises privacy and regulatory considerations, as sensing can reveal information about individuals and their activities; therefore, 3GPP includes mechanisms for privacy protection, authorization, and data handling.

Purpose & Motivation

ISAC was motivated by the desire to add a new dimension to cellular networks: environmental awareness. Traditional communication networks are blind to their surroundings; they only know about the radio channel between transmitter and receiver. Separate radar systems are expensive, require dedicated spectrum, and are often bulky. By integrating sensing into cellular infrastructure, operators can offer new services, improve network performance (e.g., beam management using sensing), and enable applications like autonomous driving and smart factories without additional hardware. The problem it solves is the lack of environmental context in wireless networks and the cost of deploying separate sensing systems.

Previous approaches to sensing in cellular networks were limited to positioning based on communication signals (e.g., OTDOA, RTT), which are designed for localizing UEs, not for detecting passive objects. Dedicated radar systems use different waveforms and spectrum, and do not benefit from the ubiquity and connectivity of cellular networks. ISAC leverages the massive investments in 5G infrastructure and spectrum to provide sensing as a service, with the potential for wide-area coverage, high resolution, and integration with communication. It also addresses the need for new revenue streams for operators and enables new use cases in automotive, industrial, and consumer domains.

The creation of ISAC specifications in 3GPP ensures global interoperability, spectrum efficiency, and coexistence with communication services. It provides a standardized framework for sensing waveforms, procedures, and performance metrics, enabling multi-vendor implementations and fostering an ecosystem. Release 19 marked the first study of ISAC in 3GPP, and Release 20 continues to mature the technology toward commercial deployment.