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What is joint communications and sensing and how does it affect the RF system design?

Joint communications and sensing (JCAS, also called joint radar-communication, JRC, or dual-function radar-communication, DFRC) uses a single RF system to simultaneously perform wireless communication and radar sensing, sharing the same hardware, waveform, and spectrum. This affects the RF system design by requiring: a waveform that serves both functions (the transmitted signal must be optimized for both data communication (high spectral efficiency, low error rate) and radar sensing (good range/velocity resolution, low sidelobes). OFDM is a strong candidate: the subcarrier structure enables data modulation while the wideband nature provides range resolution. FMCW is another candidate: the chirp waveform has excellent radar performance and can encode data in: chirp slope modulation, or embedded data symbols between chirps), antenna design (for communication: the antenna beamforms toward the user(s) for maximum SNR and minimal interference; for sensing: the antenna illuminates the sensing targets (which may be in different directions from the communication users); MIMO phased arrays with digital beamforming can simultaneously form: a communication beam toward the user, and a sensing beam toward the area of interest (or use the same beam for both with omnidirectional sensing from the communication waveform)), and signal processing (the receiver processes the same received signal for both communication (demodulating the data from the communication user) and sensing (extracting range, velocity, and angle information from the radar echo); the processing chains share the ADC and front-end but diverge in the baseband (communication: FFT + demodulation; sensing: matched filter + CFAR)).
Category: RF for Emerging Applications
Updated: April 2026
Product Tie-In: Various Components

Joint Communications and Sensing

JCAS is a key 6G technology that addresses the growing demand for both wireless connectivity and radar-like sensing in the same spectrum and hardware.

ParameterOption AOption BOption C
PerformanceHighMediumLow
CostHighLowMedium
ComplexityHighLowMedium
BandwidthNarrowWideModerate
Typical UseLab/militaryConsumerIndustrial

Technical Considerations

When evaluating joint communications and sensing and how does it affect the rf system design?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Performance Analysis

When evaluating joint communications and sensing and how does it affect the rf system design?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Design Guidelines

When evaluating joint communications and sensing and how does it affect the rf system design?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Implementation Notes

When evaluating joint communications and sensing and how does it affect the rf system design?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

  • Performance verification: confirm specifications against the application requirements before finalizing the design
  • Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
  • Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades

Practical Applications

When evaluating joint communications and sensing and how does it affect the rf system design?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Common Questions

Frequently Asked Questions

What spectrum is used?

JCAS can operate in: mmWave (28, 39, 60 GHz): wide bandwidth available. Excellent for both communication (high data rate) and sensing (fine range resolution). Already allocated for 5G and radar. Sub-6 GHz (3.5 GHz, 5 GHz): widely used for cellular and Wi-Fi. Moderate bandwidth and resolution. 77 GHz (automotive radar band): currently allocated for radar only. Future JCAS systems may use this band for combined V2X communication and radar. The trend: future spectrum allocations may explicitly support JCAS to improve spectral efficiency (one system doing two functions in the same band instead of two separate systems in different bands).

How does it affect 6G?

JCAS is a major 6G research direction: IMT-2030 (6G) vision includes JCAS as one of the six usage scenarios. 3GPP is expected to study and potentially standardize JCAS in Release 20+ (2028-2030). The 6G JCAS vision: every base station becomes a sensor (detecting: vehicles, pedestrians, drones, weather, and environmental changes), and every user device becomes a sensing node (contributing to a global sensing network). The integration of sensing into the communication network enables new services: real-time high-resolution mapping, autonomous vehicle support, and environmental monitoring.

What are the design tradeoffs?

Communication wants: high-order modulation (64-QAM, 256-QAM) for spectral efficiency (but this creates high PAPR and variable-amplitude waveforms, which have poor radar sidelobe performance). Sensing wants: constant-modulus waveforms (like chirps) for optimal radar performance (but these carry less information). The JCAS waveform design balances: data rate vs. sensing accuracy, beam allocation between communication users and sensing targets, and processing complexity (running both communication and sensing processing in real-time). Approaches: OFDM with randomized data: the random data symbols on OFDM subcarriers create a noise-like waveform that has acceptable (though not optimal) radar performance with minor modifications. Dedicated sensing subcarriers/symbols: reserve some OFDM resources for known pilot/sensing symbols that have optimal radar properties.

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