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The recently acquired mid-band frequency range (FR3) for 6G necessitates adopting extremely large aperture arrays (ELAAs) to leverage higher array gains and spatial multiplexing gains to compensate for larger path-losses compared to sub-6 GHz band and reduction of bandwidth availability compared to millimeter-waves, respectively. However, the nearfield of ELAAs may extend hundreds of meters depending on the aperture size and operating frequency. Hence, the planarwave based far-field channel models must be replaced by spherical-wave based near-field counterparts. To this end, we analyze the near-field performance of ELAA-based integrated sensing and communications (ISAC). This analysis captures the near-field spatial correlation, partial visibility due to spatially non-wide sense stationarities, erroneous channel estimates, an extended target, and clutter sources. A computationally-efficient conjugate precoding-based superimposed ISAC waveform is used at ELAAs. This waveform is further optimized via transmit power allocation to maximize the minimum achievable rate of the weakest communication user, while satisfying a sensing threshold for target detection. The achievable user rates and a target detector are derived. Our results demonstrate the potential of ELAA-based ISAC to improve the trade-off between the communication and sensing performance metrics.
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This content will become publicly available on June 8, 2026
Trade-Off Between Probability of Detection and Achievable Rate in Near-Field ISAC Systems
The transition to millimeter-wave and sub-THz frequency bands necessitates that the base-stations (BSs) utilize extra-large antenna arrays (ELAA) to compensate for the associated huge path-losses. However, when higher frequencies and shorter transmission distances are utilized, the spherical wave curvature can no longer be neglected. Hence, the ELAAbased wireless systems tend to operate primarily in the near-field. Thus, the far-field channel models used for near-field users may detrimentally affect wireless system designs and performance gains. To this end, we investigate the impact of mismatches between far-field and near-field channel models/precoders on the performance of ELAA-based integrated sensing and communication (ISAC). To this end, the achievable user rates are derived for the near-field. Two detectors for sensing a target are designed based on known/unknown BS/target channels. The performance of these detectors are investigated by deriving the probability of detection and probability of false-alarm. A transmit power optimization procedure is also proposed to maximize the minimum achievable user rate, while ensuring a power threshold for sensing. Numerical results are used to study the fundamental trade-off between the probability of detection and achievable rates for near-field ELAA-based ISAC. We unveil that ELAAs can be leveraged to improve the ISAC performance trade-offs.
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- Award ID(s):
- 2326621
- PAR ID:
- 10652288
- Publisher / Repository:
- IEEE
- Date Published:
- Page Range / eLocation ID:
- 1766 to 1771
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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