Distributed Joint User Activity Detection, Channel Estimation, and Data Detection via Expectation Propagation in Cell-Free Massive MIMO
<|reference_start|>Distributed Joint User Activity Detection, Channel Estimation, and Data Detection via Expectation Propagation in Cell-Free Massive MIMO: We consider the uplink of a grant-free cell-free massive multiple-input multiple-output (GF-CF-MaMIMO) system. We propose an algorithm for distributed joint activity detection, channel estimation, and data detection (JACD) based on expectation propagation (EP) called JACD-EP. We develop the algorithm by factorizing the a posteriori probability (APP) of activities, channels, and transmitted data, then, mapping functions and variables onto a factor graph, and finally, performing a message passing on the resulting factor graph. If users with the same pilot sequence are sufficiently distant from each other, the JACD-EP algorithm is able to mitigate the effects of pilot contamination which naturally occurs in grant-free systems due to the large number of potential users and limited signaling resources. Furthermore, it outperforms state-of-the-art algorithms for JACD in GF-CF-MaMIMO systems.<|reference_end|>
@article{forsch2024distributed,
    title={Distributed Joint User Activity Detection, Channel Estimation, and Data
  Detection via Expectation Propagation in Cell-Free Massive MIMO},
    author={Christian Forsch, Alexander Karataev, Laura Cottatellucci},
    journal={arXiv preprint arXiv:2405.09914},
    year={2024},
    archivePrefix={arXiv},
    eprint={2405.09914},
    primaryClass={cs.IT eess.SP math.IT}
}