ISAC, short for integrated sensing and communication, is a network design approach in which the same radio spectrum, waveforms and hardware are used both to transmit data and to sense the physical environment, much like a radar. In telecommunications, it is one of the defining research directions of 6G & future networks, and it is listed as a new usage scenario in IMT-2030, the ITU framework for 6G.
The idea is that base stations and devices already emit and receive radio signals continuously. By analyzing echoes, delays, Doppler shifts and angles of those signals, the network can detect, locate and track objects such as vehicles, drones or people, without dedicated radar equipment. This turns the mobile network into a wide-area sensing platform in addition to a connectivity service.
How integrated sensing and communication works
Radar and wireless communication rely on the same physics: an electromagnetic wave travels, reflects and is received. Radar extracts information from the channel itself, while communication extracts information carried by the signal. ISAC combines both functions by designing signals and receivers that serve both purposes at once.
In a typical monostatic setup, a base station transmits a signal and receives its own reflections, which requires full-duplex operation or careful isolation between transmit and receive paths. In a bistatic or multistatic setup, one node transmits and another receives, which avoids self-interference but requires tight synchronization between sites.
| Configuration | Transmitter and receiver | Main advantage | Main difficulty |
|---|---|---|---|
| Monostatic | Same node | Simple geometry and timing | Self-interference cancellation |
| Bistatic | Two separate nodes | No full-duplex requirement | Clock and position synchronization |
| Multistatic | Several cooperating nodes | Wide coverage and accuracy | Complex coordination and data fusion |
| Device-based | User equipment senses or assists | Dense, close-range sensing | Battery use and privacy |
The sensing performance depends on familiar radar parameters. Bandwidth determines range resolution, roughly 15 centimeters for 1 GHz of bandwidth; antenna aperture determines angular resolution; and observation time determines velocity resolution through the Doppler effect. This is why ISAC research focuses on wide bands in the upper mid-band, millimeter-wave and terahertz communication ranges, combined with large antenna arrays.
Levels of integration
ISAC is not a single technique but a spectrum of integration depths, from simple resource sharing to a fully joint design. Each step increases efficiency and also complexity.
| Level | What is shared | Typical example |
|---|---|---|
| Coexistence | Spectrum only, with interference management | Radar and cellular bands side by side |
| Resource sharing | Time, frequency or beam resources | Dedicated sensing slots in a frame |
| Hardware sharing | Antennas and radio chains | Base station radio performs both tasks |
| Joint waveform design | One signal optimized for both | OFDM symbols used for data and sensing |
| Network-level ISAC | Sensing data fused across the network | Many sites track objects together |
Most near-term proposals use OFDM-based waveforms, the same family used in 4G and 5G, because they are already deployed and can be processed for sensing with well-known algorithms. Alternative waveforms such as OTFS are studied for high-mobility scenarios, where they may offer better resilience to Doppler effects.
Use cases for network-based sensing
The main attraction of ISAC is that sensing becomes available wherever the network already provides coverage. The table lists use cases that standardization bodies and industry groups commonly study.
| Use case | What is sensed | Typical requirement |
|---|---|---|
| Drone detection | Unauthorized or cooperative drones | Detection at hundreds of meters |
| Traffic monitoring | Vehicles and pedestrians at intersections | Sub-meter positioning, low latency |
| Rail and level crossings | Obstacles on tracks | High reliability |
| Indoor presence and gestures | People, motion, breathing | Centimeter-scale sensitivity |
| Environment mapping | Buildings and terrain | Improves beam management |
Sensing also helps communication itself. Knowing where users and obstacles are allows sensing-assisted beam management, which can reduce the overhead of searching for the best beam, especially at millimeter-wave and higher frequencies where beams are narrow.
ISAC compared with neighboring 6G concepts
ISAC overlaps with several other 6G research topics, and the boundaries are often blurred. It differs from classic positioning, which estimates the location of a cooperating device, because ISAC can detect passive objects that carry no radio at all.
It also works closely with a network digital twin, which can use sensing data as a live input, and with an AI-native network, because machine learning is increasingly used to extract targets from noisy reflections. Reconfigurable intelligent surfaces can extend sensing coverage by redirecting signals around obstacles.
Compared with dedicated radar, network-based sensing usually offers lower peak resolution and less transmit power devoted to sensing, but far greater geographic coverage at marginal cost. It is therefore best seen as a complement to automotive or aviation radar, not a replacement, particularly where safety certification requires purpose-built sensors.
Technical and societal challenges
ISAC introduces a fundamental trade-off: resources used for sensing are not available for data, and a waveform optimized for one task is rarely optimal for the other. Operators will need clear policies on how much capacity to devote to sensing in each situation.
- Self-interference in monostatic sensing requires advanced full-duplex hardware.
- Synchronization of distributed nodes must reach nanosecond-level timing for accurate ranging.
- Clutter from buildings and static objects must be removed to find moving targets.
- Privacy is a serious concern, because a network that can sense people raises questions of consent and data protection.
- Standardization of sensing services, interfaces and exposure to third parties is still in progress.
Initial ISAC features are expected to appear in 5G-Advanced releases as studies and limited capabilities, with broader integration targeted for the first 6G systems around the end of the decade. Precise timelines and capabilities remain subject to standardization outcomes.
In simple terms
ISAC means teaching a mobile network to see as well as talk. Cell towers already send radio waves everywhere. Some of those waves bounce off cars, drones and buildings and come back, just as sound echoes in a canyon.
By listening carefully to those echoes, the network can tell where things are and how fast they move, a little like a bat finding insects in the dark. The same equipment that carries your phone calls could then also warn about a drone near an airport or a pedestrian at a busy crossing.
A practical example
A city wants to improve safety at a complex intersection where pedestrians are often hidden by buses. Instead of installing separate radar units, the local mobile operator enables a multistatic sensing service on three nearby base stations operating in a wide band of spectrum.
The base stations detect pedestrians and cyclists from the reflections of their regular signals and estimate their positions to within about half a meter. Connected vehicles approaching the intersection receive alerts about road users they cannot see. The same sensing data helps the network steer beams toward moving cars, so the operator improves both road safety and connection quality with existing infrastructure.