Cramer-Rao Bounds for Activity Detection in Conventional and Fluid Antenna Systems
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2026
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866910151739441152 |
|---|---|
| author | Zhang, Zhentian Wong, Kai-Kit Jiang, Hao Masouros, Christos Chae, Chan-Byoung |
| author_facet | Zhang, Zhentian Wong, Kai-Kit Jiang, Hao Masouros, Christos Chae, Chan-Byoung |
| contents | In this letter, we develop a unified Cramér-Rao bound (CRB) framework to characterize the fundamental performance limits of transmission activity detection in fluid antenna systems (FASs) and conventional multiple fixed-position antenna (FPA) systems. To facilitate CRB analysis applicable to activity indicators, we relax the binary activity states to continuous parameters, thereby aligning the bound-based evaluation with practical threshold-based detection decisions. Closed-form CRB expressions are derived for two representative detection formulations, namely covariance-oriented and coherent models. Moreover, for single-antenna FASs, we obtain a closed-form coherent CRB by leveraging random matrix theory. The results demonstrate that CRB-based analysis provides a tractable and informative benchmark for evaluating activity detection across architectures and detection schemes, and further reveal that FASs can deliver strong spatial-diversity gains with significantly reduced complexity. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_11901 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Cramer-Rao Bounds for Activity Detection in Conventional and Fluid Antenna Systems Zhang, Zhentian Wong, Kai-Kit Jiang, Hao Masouros, Christos Chae, Chan-Byoung Information Theory In this letter, we develop a unified Cramér-Rao bound (CRB) framework to characterize the fundamental performance limits of transmission activity detection in fluid antenna systems (FASs) and conventional multiple fixed-position antenna (FPA) systems. To facilitate CRB analysis applicable to activity indicators, we relax the binary activity states to continuous parameters, thereby aligning the bound-based evaluation with practical threshold-based detection decisions. Closed-form CRB expressions are derived for two representative detection formulations, namely covariance-oriented and coherent models. Moreover, for single-antenna FASs, we obtain a closed-form coherent CRB by leveraging random matrix theory. The results demonstrate that CRB-based analysis provides a tractable and informative benchmark for evaluating activity detection across architectures and detection schemes, and further reveal that FASs can deliver strong spatial-diversity gains with significantly reduced complexity. |
| title | Cramer-Rao Bounds for Activity Detection in Conventional and Fluid Antenna Systems |
| topic | Information Theory |
| url | https://arxiv.org/abs/2602.11901 |