6G Integrated Sensing and Communications (ISAC)

Introduction

The sixth generation (6G) of wireless communications is expected to fundamentally transform mobile networks from pure communication platforms into intelligent sensing and communication infrastructures. One of the most revolutionary technologies enabling this transformation is Integrated Sensing and Communications (ISAC).

ISAC combines wireless communication and environmental sensing within a unified network infrastructure, allowing the same radio signals, spectrum, antennas, and hardware resources to simultaneously support data transmission and sensing functionalities. Unlike traditional networks where communication and sensing systems operate independently, ISAC enables cellular networks to act as large-scale distributed radar systems capable of detecting, locating, tracking, imaging, and understanding objects and environments while maintaining high-speed communications.

A 6G ISAC tower sends out a single wireless signal that does two jobs at once — it talks to your devices (solid blue waves) AND bounces back from objects to "see" what's around it (dashed amber waves), just like a bat using echolocation while also singing.

This is expected to become one of the defining pillars of 6G, enabling applications such as autonomous transportation, smart factories, digital twins, healthcare monitoring, drone traffic management, industrial robotics, immersive XR experiences, environmental monitoring, and military operations.

According to research initiatives from the International Telecommunication Union (ITU), 3GPP, Next G Alliance, Hexa-X, and major industry players, ISAC is expected to become a native capability of future 6G networks.

Historically, communication and sensing systems evolved independently.

Communication systems focused on:

• Delivering information between users

• Maximizing throughput

• Reducing latency

• Improving reliability

Sensing systems focused on:

• Object detection

• Distance measurement

• Velocity estimation

• Environmental awareness

Examples include:

• Radar systems

• LiDAR

• Sonar

• Cameras

Traditionally these systems required:

• Dedicated hardware

• Dedicated spectrum

• Separate infrastructure

This separation leads to:

• Spectrum inefficiency

• Higher deployment cost

• Increased power consumption

• Infrastructure duplication

The growing scarcity of spectrum resources and increasing demand for environmental awareness motivated researchers to merge these functionalities.

ISAC emerged as the solution.

Instead of using separate systems, a single 6G radio network performs:

• Communication

• Positioning

• Localization

• Object detection

• Motion tracking

• Environment mapping

using the same waveform and infrastructure.

2. Why ISAC is Important for 6G

6G networks aim to provide:

• Tbps data rates

• Sub-millisecond latency

• AI-native operation

• Native sensing capability

• Digital twin support

• Extreme positioning accuracy

Future applications require networks to understand their surroundings.

Examples:

Autonomous Vehicles

Vehicles need:

• Communication with infrastructure

• Detection of nearby vehicles

• Pedestrian tracking

• Road condition awareness

Smart Factories

Industrial robots require:

• Machine communication

• Worker tracking

• Asset monitoring

• Safety monitoring

Digital Twins

Digital twins require continuous real-world updates through sensing.

ISAC enables all these functions using one network.

3. Evolution Toward ISAC

4G Era

Focus:

• Mobile broadband

No sensing capability.

5G Era

Limited sensing capabilities emerged through:

• Positioning Reference Signals (PRS)

• Beam management

• CSI measurements

Applications remained communication centric.

5G Advanced

Enhanced positioning and localization features were introduced.

6G Era

Native sensing becomes a core network function.

Communication and sensing are designed together from the beginning.

4. Fundamental Principle of ISAC

A wireless signal transmitted for communication can also be used for sensing.

When a signal encounters an object:

• Reflection occurs

• Scattering occurs

• Doppler shifts occur

By analyzing reflected signals, the network can determine:

• Distance

• Velocity

• Direction

• Shape

• Motion patterns

Thus, one transmission serves two purposes:

1. Deliver data

2. Sense environment

This concept forms the foundation of ISAC.

5. 6G ISAC Reference Architecture

High-Level ISAC Architecture

6G core network

The core is the intelligence orchestration layer, running three specialized platforms. The AI/ML engine handles federated model training and distributes inference models to the RAN edge. The digital twin platform maintains a live, synchronized virtual replica of the physical environment — updated in real time from ISAC sensing reports — used for what-if simulation and proactive resource management. The sensing analytics platform aggregates raw sensing KPIs from multiple gNBs into network-wide scene maps, coverage reports, and sensing-as-a-service APIs for vertical applications.

6G RAN ISAC-enabled

This is where the ISAC waveform lives. The CU/DU split follows O-RAN principles: the CU handles RRC/PDCP (including ISAC session management), the DU handles MAC/PHY (including the dual-function waveform scheduling). The RAN-side AI engine runs as a near-RT RIC xApp — it performs beam prediction, channel estimation, and adaptive waveform configuration in under 10 ms. The edge cloud (MEC) co-located with the gNB runs the AV path planner and digital twin synchronization, keeping round-trip latency under 5 ms. The ISAC processing unit executes the four-stage sensing pipeline: detection (CFAR thresholding), tracking (Kalman/particle filter), localization (AoA + ToF fusion for centimeter accuracy), and environment mapping (occupancy grid construction).

Massive MIMO / smart antennas

The antenna array is the physical boundary between waveform and air. With 256+ elements, hybrid beamforming allows the system to simultaneously steer a communication beam at a UE and a sensing beam at a region of interest — both encoded into a single OFDM waveform using DFRC (dual-function radar-communication) techniques. The echo returns enter separate receive ports and are routed to the ISAC processing unit.

End nodes

These are the objects the system both communicates with and senses. Vehicles and drones are active UEs contributing V2X sidelink sensing data cooperatively. Humans, passive assets, and machines are sensing targets — detected purely from reflected echo without requiring any device on their person.

6. Functional Components of ISAC

Communication Function

Responsible for:

• User data transmission

• QoS management

• Mobility management

• Beamforming

Sensing Function

Responsible for:

• Object detection

• Object classification

• Localization

• Motion estimation

AI Engine

Processes sensed information and enables:

• Scene understanding

• Object prediction

• Behavioral analysis

Digital Twin Engine

Creates virtual representations of physical environments.

7. Key Technology Enablers for ISAC

Massive MIMO

Massive MIMO provides:

• Hundreds of antenna elements

• Highly directional beams

• Spatial diversity

Benefits:

• High-resolution sensing

• Improved localization

• Better tracking accuracy

Massive MIMO effectively turns base stations into large radar arrays.

Millimeter Wave (mmWave)

Frequency range:

• 24 GHz – 100 GHz

Advantages:

• Large bandwidth

• High spatial resolution

Enables:

• Fine object detection

• Accurate imaging

Sub-THz Communications

6G is expected to utilize:

• 100 GHz – 300 GHz

Benefits:

• Extremely large bandwidth

• Millimeter-level sensing resolution

Applications:

• Industrial automation

• Holographic communications

Reconfigurable Intelligent Surfaces (RIS)

RIS consists of programmable reflecting surfaces.

Functions:

• Beam steering

• Signal enhancement

• Reflection control

Benefits for ISAC:

• Eliminate sensing blind spots

• Improve coverage

• Enhance localization accuracy

AI and Machine Learning

AI is the brain of ISAC.

Tasks include:

• Object recognition

• Environment mapping

• Trajectory prediction

• Sensor fusion

Without AI, large-scale ISAC would be impractical.

Edge Computing

ISAC generates massive sensing data.

Edge computing provides:

• Real-time processing

• Reduced latency

• Faster decision making

Critical for:

• Autonomous driving

• Industrial automation

Network Digital Twins

Digital twins maintain virtual replicas of physical environments.

Sensed information continuously updates the twin.

Applications:

• Smart cities

• Factories

• Transportation systems

Joint Waveform Design

Traditional systems use separate waveforms.

ISAC uses unified waveforms supporting:

• Communication

• Radar sensing

Examples:

• OFDM-based ISAC

• OTFS-based ISAC

• Advanced AI-generated waveforms

8. ISAC Signal Processing Workflow

The diagram shows the complete ISAC signal processing pipeline organized into three functional phases, with a feedback loop from the final AI stage back to the transmitter for closed-loop beam adaptation. Here is what each phase covers:

Transmission phase  — the gNB emits a single dual-function waveform (typically OFDM-based, as in 3GPP DFRC proposals) that simultaneously carries a data payload to the user equipment and acts as a radar probe signal. This shared-waveform approach is the defining property of ISAC — no separate radar band or hardware needed.

Reception phase— the reflected echo returns to the gNB's receive array. A matched filter and range-Doppler FFT extract range and velocity for each scatterer. CFAR (constant false alarm rate) thresholding then separates genuine target returns from noise, producing a list of detected objects with range, Doppler, and angle estimates.

Intelligence phase— localization fuses angle-of-arrival and time-of-flight measurements (potentially from multiple cooperative nodes) to yield centimeter-accurate 3D positions. A Kalman or particle filter maintains consistent trajectories across frames. Finally, a deep neural network classifies object type (vehicle, pedestrian, cyclist), estimates velocity vectors, and feeds the result directly into the autonomous vehicle's path planner.

The feedback arc on the left represents adaptive beam management — the AI layer continuously updates the transmit beamforming weights to keep sensing beams pointed at high-priority targets, closing the loop between perception and transmission. Click any stage in the diagram to explore it further.

9. Real-Time Use Cases and Applications

Autonomous Transportation

ISAC enables:

• Vehicle-to-everything communication

• Pedestrian detection

• Collision avoidance

• Traffic monitoring

Future roads may rely on cellular ISAC rather than standalone radar systems.

Smart Factories

Industrial environments require:

• Worker safety monitoring

• Robot coordination

• Asset tracking

ISAC provides:

• Communication

• Positioning

• Motion tracking

through one network.

Drone Traffic Management

Urban skies will host thousands of drones.

ISAC supports:

• Drone tracking

• Collision prevention

• Flight path optimization

Healthcare Monitoring

ISAC can monitor:

• Heart rate

• Breathing patterns

• Movement

without wearable devices.

Applications include:

• Elderly care

• Hospital monitoring

• Remote patient observation

Smart Cities

Applications include:

• Traffic monitoring

• Crowd management

• Emergency response

Networks become city-wide sensing platforms.

Extended Reality (XR)

Future XR systems require:

• User tracking

• Gesture recognition

• Spatial awareness

ISAC enables centimeter-level positioning.

Industrial Robotics

Factories require:

• Robot localization

• Worker detection

• Dynamic path planning

ISAC enables safer human-machine collaboration.

Railway Monitoring

ISAC can detect:

• Track intrusions

• Obstacles

• Train movements

Improving transportation safety.

Maritime Monitoring

Applications include:

• Ship tracking

• Harbor management

• Coastal surveillance

Defense and Security

Potential applications:

• Battlefield awareness

• Target detection

• Surveillance

Future military networks may integrate sensing and communication capabilities.

10. ISAC in Autonomous Vehicle Scenario

6G ISAC in an autonomous vehicle scenario integrates radar-style sensing and broadband communication into a single waveform transmitted by the gNB base station — eliminating the need for separate sensing infrastructure.

ISAC Functions:1. Vehicle Communication2. Vehicle Tracking3. Pedestrian Detection4. Velocity Estimation5. Collision Prediction

Here's what each node does:

gNB base station — the central orchestrator. It broadcasts dual-function waveforms that simultaneously carry user data and illuminate the environment for sensing. Channel estimates from the reflected signal are processed to produce a real-time map of vehicle positions, speeds, and even pedestrian locations.

Vehicle A & B (V2X nodes) — each vehicle runs its own on-board radar via ISAC waveforms and shares the extracted sensing data with the gNB and peer vehicles over V2V sidelink (3GPP Rel-17/18 PC5 interface). This cooperative sensing fills blind spots that a single node cannot cover.

Smart traffic signal (V2I) — receives phase and timing advisories from the gNB derived from real-time traffic sensing. It also relays its own detector data back upstream, closing the loop for intersection management.

Pedestrian — a passive sensing target. The gNB and vehicles detect the pedestrian from reflected ISAC waveforms without requiring any device on the pedestrian. The multi-node geometry gives centimeter-accurate localization even around corners (cooperative NLOS sensing, a key 6G feature).

Key ISAC advantage: a single 6G resource block carries both the data payload and the sensing reference signal, cutting spectral overhead and enabling sub-millisecond reaction latency — critical for AV collision avoidance at urban speeds.

11. ISAC Performance Metrics

Key metrics include:

Communication Metrics

• Throughput

• Spectral Efficiency

• Reliability

• Latency

Sensing Metrics

• Detection Probability

• Localization Accuracy

• Range Resolution

• Velocity Resolution

• Tracking Accuracy

Joint Metrics

• Sensing-Communication Tradeoff

• Energy Efficiency

• Resource Utilization

12. Challenges in ISAC

Although promising, ISAC faces significant challenges.

Spectrum Sharing Conflict

Communication and sensing compete for:

• Power

• Bandwidth

• Time resources

Balancing both remains difficult.

Waveform Design Complexity

Waveforms must satisfy:

• High communication throughput

• Accurate sensing performance

Achieving both simultaneously is challenging.

Hardware Constraints

ISAC requires:

• High-speed ADCs

• Large antenna arrays

• High processing capability

Cost remains a concern.

Synchronization Issues

Accurate sensing requires:

• Time synchronization

• Frequency synchronization

Errors can significantly degrade performance.

Multi-Target Detection

Dense environments contain:

• Vehicles

• Humans

• Buildings

• Drones

Distinguishing multiple targets is difficult.

Privacy Concerns

Networks capable of sensing people raise concerns regarding:

• Surveillance

• Data collection

• User privacy

Future regulations will be required.

Security Risks

Potential threats include:

• Sensing spoofing

• False target injection

• Jamming attacks

New security mechanisms are necessary.

AI Model Complexity

ISAC generates enormous datasets.

Training AI models requires:

• High computational resources

• Large datasets

• Continuous updates

13. ISAC Standardization Activities

Several organizations are actively defining ISAC requirements.

3GPP

Studying:

• Integrated sensing use cases

• Waveform design

• Radio architecture impacts

Likely introduced progressively across future 6G releases.

ITU

Identifies sensing as a major 6G capability.

Next G Alliance

Promoting North American 6G vision including ISAC.

Hexa-X

European flagship 6G initiative actively researching ISAC.

IMT-2030 Promotion Group

China's major 6G research platform with strong ISAC focus.

14. Latest Trends in ISAC

AI-Native ISAC

AI directly controls:

• Beamforming

• Resource allocation

• Object recognition

Cell-Free ISAC

Distributed antennas collaborate for sensing.

Benefits:

• Improved coverage

• Better localization

RIS-Assisted ISAC

RIS enhances sensing performance in difficult environments.

Semantic ISAC

Networks understand the meaning of sensed information.

Instead of raw data:

• Objects

• Activities

• Intentions

are identified.

Distributed Cooperative Sensing

Multiple base stations jointly sense environments.

Creates a network-wide perception system.

Digital Twin Integration

Real-time digital twins continuously update using ISAC measurements.

THz ISAC

Sub-THz and THz frequencies enable:

• Ultra-high-resolution sensing

• High-definition environmental imaging

AI-RAN + ISAC

AI-RAN architectures integrate AI processing directly into RAN infrastructure.

This enables:

• Real-time perception

• Predictive networking

• Autonomous optimization

Companies Working on ISAC

Nokia

Research focus:

• Hexa-X

• 6G sensing architecture

• AI-enabled ISAC

Ericsson

Developing:

• Joint communication-sensing systems

• 6G radio architecture

• Network sensing frameworks

Huawei

Among the most active ISAC researchers.

Focus areas:

• THz sensing

• AI-native sensing

• Smart city applications

Samsung

Researching:

• THz communications

• Joint radar-communication systems

Qualcomm

Investigating:

• Device-based sensing

• AI-enabled ISAC platforms

ZTE

Leading multiple 6G sensing research initiatives.

China Mobile

Large-scale ISAC trials and demonstrations.

NTT DOCOMO

Researching:

• Human sensing

• Smart city applications

• Digital twin integration

Keysight Technologies

Developing:

• ISAC test platforms

• Channel emulation solutions

Rohde & Schwarz

Supporting:

• ISAC waveform testing

• 6G validation environments

15. Future Vision of ISAC

Future 6G networks will not merely connect devices.

They will:

• Observe environments

• Understand contexts

• Predict events

• Assist autonomous systems

A 6G base station may simultaneously:

• Deliver Tbps connectivity

• Detect vehicles

• Track drones

• Monitor crowds

• Update digital twins

This transforms cellular infrastructure into a global sensing platform.

Conclusion

Integrated Sensing and Communications (ISAC) represents one of the most transformative technologies envisioned for 6G. By merging communication and sensing functionalities into a unified platform, ISAC enables wireless networks to become intelligent perception systems capable of understanding and interacting with the physical world.

The convergence of Massive MIMO, AI/ML, RIS, edge computing, digital twins, mmWave, and sub-THz communications creates the technological foundation necessary for large-scale ISAC deployment. Applications span autonomous transportation, smart manufacturing, healthcare, XR, smart cities, defense, logistics, and industrial automation.

Despite challenges involving waveform design, spectrum sharing, hardware complexity, privacy, and security, rapid progress by industry leaders, academia, and standardization bodies suggests ISAC will become a cornerstone capability of 6G networks. The ultimate vision is a world where wireless networks no longer simply transport information but actively sense, understand, and interact with their environments, enabling a truly intelligent and autonomous digital society.

References

1.       3GPP TR 22.837 — Feasibility study on integrated sensing and communication, https://www.3gpp.org/ftp/Specs/archive/22_series/22.837/

2.       3GPP TS 22.137 — Service requirements for ISAC (Release 19), https://www.3gpp.org/ftp/Specs/archive/22_series/22.137/

3.       https://discovery.ucl.ac.uk/id/eprint/10147120/1/Integrated_Sensing_and_Communications_Towards_Dual-functional_Wireless_Networks_for_6G_and_Beyond.pdf?utm_source=chatgpt.com

4.       https://arxiv.org/abs/2108.07165, Integrated Sensing and Communications: Toward Dual-Functional Wireless Networks for 6G and Beyond

5.       Wei et al. — "Toward deeper environmental understanding: event-level sensing for intelligent 6G ISAC" (arXiv 2606.14223, 2025)