Phased Ultra Massive Array (PUMA)

TL;DR

PUMA introduces a phased array framework leveraging fluid antenna systems at UEs, enabling interference mitigation and high efficiency for 6G massive connectivity without complex CSI or interference cancellation.

Contribution

It presents a novel PUMA architecture combining phased arrays with fluid antennas, reducing hardware complexity while enhancing interference management and data rates.

Findings

PUMA outperforms FAMA and CUMA in simulations.

It achieves high antenna gain with minimal RF chains.

Theoretical analysis confirms significant data rate improvements.

Abstract

This paper proposes a novel multiple-access framework, termed the phased ultra massive antenna array (PUMA), which exploits the distinctive spatial flexibility of fluid antenna systems (FAS) at the user equipment (UE). Building upon fluid antenna multiple access (FAMA) and compact ultra-massive antenna array (CUMA), PUMA incorporates a phased array for signal aggregation. This architecture enables the UE to inherently mitigate co-user interference within the spatial domain without necessitating channel state information (CSI) for precoding at the base station (BS) or complex interference cancellation at each UE. A primary advantage of PUMA lies in its hardware efficiency: by implementing phase shifting and signal combining in the analog domain, it achieves high antenna gain while requiring only a minimal number of radio-frequency (RF) chains, potentially a single RF chain. Comprehensive theoretical analysis of the achievable data rate is provided, complemented by extensive simulations that validate the framework. The results demonstrate that PUMA markedly outperforms FAMA and CUMA architectures, particularly for UEs with a single RF chain, offering a robust and scalable solution for interference-insensitive massive connectivity in sixth-generation (6G) systems.