What Is Integrated Sensing and Communication?

Integrated sensing and communication, commonly abbreviated ISAC, is a design approach in which a single wireless system performs radio sensing and data transmission using shared spectrum, shared hardware, and often a shared waveform. Rather than operating a radar and a communication link side by side, an ISAC transmitter sends a signal that carries information to a receiver while the echoes returning from the environment are processed to estimate the range, velocity, angle, or presence of objects. The concept draws on radar signal processing, information theory, and multi-antenna communication design, and it is treated in the research literature under names including joint radar and communication and RadCom.

Interest in ISAC grew from a practical constraint. Millimeter wave and upper mid-band spectrum allocations that suit high-rate communication also suit fine-resolution sensing, and cellular base stations already deploy the large antenna arrays and wide bandwidths that radar performance depends on. Reusing that infrastructure avoids duplicating hardware and reduces the mutual interference that separate collocated systems create. ISAC has consequently become a defining feature of 6G research programs and of 5G-Advanced study items, as surveyed in work on ISAC signal design toward 5G-A and 6G.

Waveform and Signal Design

The central design question is what signal to transmit. Communication waveforms such as OFDM are optimized for spectral efficiency and randomness, while radar waveforms are optimized for a sharp ambiguity function and low autocorrelation sidelobes, and these goals conflict. Three broad strategies exist: adapt a communication waveform for sensing, embed information in a radar waveform, or synthesize a jointly optimized waveform from the start. OFDM-based sensing has become the dominant practical choice because the cyclic prefix structure allows range and Doppler estimation by simple element-wise division in the frequency domain. Precoding and beamforming across a multi-antenna array then trade sensing beam gain against communication rate, a tradeoff formalized as a performance boundary between estimation accuracy and channel capacity.

Transceiver Architecture and Hardware

Sharing a front end between functions raises problems that do not arise in either system alone. A monostatic ISAC node must receive weak echoes while its own transmitter is active, which demands strong self-interference cancellation in the analog and digital domains. Phase noise, nonlinear power amplifiers, and limited converter dynamic range degrade sensing accuracy more sharply than they degrade a coded data link. Research on ISAC transceiver architectures has examined full-duplex front ends, subarray partitioning, and bistatic arrangements in which one base station illuminates the scene and a neighboring node receives, avoiding the isolation problem entirely at the cost of tight synchronization.

Channel Modeling and Evaluation

Evaluating an ISAC system requires a channel model that represents both the propagation path to a communication receiver and the scattering behavior of the targets being sensed, including their radar cross section and motion. Conventional cellular channel models describe only the former. Standardization bodies and academic groups have therefore extended geometry-based stochastic models with target components and shared scatterers, an area reviewed in a survey of ISAC channel modeling. Consistent models matter because sensing metrics such as detection probability and Cramer-Rao bounds on parameter estimation cannot otherwise be compared across proposals.

Applications

Integrated sensing and communication has applications in a range of areas, including:

• Vehicular networks, where a roadside unit both communicates with vehicles and tracks them
• Unmanned aerial vehicle detection and low-altitude airspace monitoring
• Indoor human activity sensing, gesture interfaces, and fall detection
• Industrial automation with simultaneous asset tracking and control signaling
• Environmental and weather sensing using existing cellular infrastructure