Feasibility of Common-Stream-Only Sensing in ZF-RSMA with Imperfect CSIT
Abstract
Reusing the Rate-Splitting Multiple Access (RSMA) common stream for sensing eliminates dedicated probing signals in Integrated Sensing and Communication (ISAC), but creates a feasibility bottleneck: the common-power fraction must simultaneously support common decoding, private decoding, and target detection. This paper investigates this tradeoff in downlink zero-forcing RSMA with imperfect channel state information at the transmitter (CSIT) and imperfect successive interference cancellation (SIC). With the common beam fixed over a sensing dwell through sensing geometry, the common-power fraction becomes the sole design variable. We prove that the communication-feasible set is either a closed interval or empty. Analytical outage expressions localize these endpoints, revealing a high-signal-to-noise ratio (SNR) floor-ceiling effect: common decoding dictates a common-power floor, while imperfect CSIT and SIC impose a private-decoding ceiling. For sensing, the conditional detection constraint is affine, preserving the interval structure. A geometry-matched common beam ensures monotonic detection improvement, reducing joint-feasibility check to the communication-feasible upper endpoint. Simulations validate our analysis, identifying regimes where common-stream-only sensing is viable.
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BibTeX
@misc{harsha2026feasibility,
title = {{Feasibility of Common-Stream-Only Sensing in ZF-RSMA with Imperfect CSIT}},
author = {Surya Harsha and Shankar Prakriya},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41744},
eprint = {2610.41744},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41744},
}
RIS
TY - UNPB
TI - Feasibility of Common-Stream-Only Sensing in ZF-RSMA with Imperfect CSIT
AU - Surya Harsha
AU - Shankar Prakriya
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2610.41744
UR - https://arxiv.org/abs/2610.41744
AB - Reusing the Rate-Splitting Multiple Access (RSMA) common stream for sensing eliminates dedicated probing signals in Integrated Sensing and Communication (ISAC), but creates a feasibility bottleneck: the common-power fraction must simultaneously support common decoding, private decoding, and target detection. This paper investigates this tradeoff in downlink zero-forcing RSMA with imperfect channel state information at the transmitter (CSIT) and imperfect successive interference cancellation (SIC). With the common beam fixed over a sensing dwell through sensing geometry, the common-power fraction becomes the sole design variable. We prove that the communication-feasible set is either a closed interval or empty. Analytical outage expressions localize these endpoints, revealing a high-signal-to-noise ratio (SNR) floor-ceiling effect: common decoding dictates a common-power floor, while imperfect CSIT and SIC impose a private-decoding ceiling. For sensing, the conditional detection constraint is affine, preserving the interval structure. A geometry-matched common beam ensures monotonic detection improvement, reducing joint-feasibility check to the communication-feasible upper endpoint. Simulations validate our analysis, identifying regimes where common-stream-only sensing is viable.
ER -