A Narrowband Fully-Analog Multi-Antenna Transmitter

2026-02-03

AI Summary

This work addresses the high power consumption bottleneck of digital radio-frequency (RF) chains in narrowband multi-antenna systems by proposing a fully analog N-antenna transmitter architecture. The design requires only a single coherent RF source and 2N−1 tunable real-valued degrees of freedom—comprising adjustable power dividers and phase shifters—to precisely synthesize any desired complex excitation vector. The key innovation lies in reframing the complex excitation synthesis problem as a unitary state preparation task, enabling a deterministic O(N)-complexity programming algorithm that achieves symbol-level updates without iterative optimization. Simulations based on commercial off-the-shelf component models demonstrate that, for N ≤ 16, the proposed architecture substantially reduces DC power consumption in the RF front end, thereby validating its feasibility as an energy-efficient narrowband fully analog transmitter.

Technology Category

• Machine Learning: Hardware-aware ML
• Search and Optimization: Sampling/Simulation-based Search
• Cognitive Modeling & Cognitive Systems: Analogy

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

This paper proposes a narrowband fully-analog $N$-antenna transmitter that emulates the functionality of a narrowband fully-digital $N$-antenna transmitter. Specifically, in symbol interval $m$, the proposed fully-analog transmitter synthesizes an arbitrary complex excitation vector $\bm x[m]\in\mathbb{C}^N$ with prescribed total power $\|\bm x[m]\|_2^2=P$ from a single coherent RF tone, using only tunable phase-control elements embedded in a passive interferometric programmable network. The programmable network is excited through one input port while the remaining $N - 1$ input ports are impedance matched. In the ideal lossless case, the network transfer is unitary and therefore redistributes RF power among antenna ports without dissipative amplitude control. The synthesis task is posed as a unitary state-preparation problem: program a unitary family so that $\bm V(\bm\varphi)\bm e_1=\bm c$, where $\bm c=\bm x/\sqrt{P}$ and $\|\bm c\|_2=1$. We provide a constructive realization and a closed-form programming rule: a binary magnitude-splitting tree allocates the desired per-antenna magnitudes $|c_n|$ using $N -1$ tunable split ratios, and a per-antenna output phase bank assigns the target phases using $N$ tunable phase shifts. The resulting architecture uses $2N-1$ real tunable degrees of freedom and admits a deterministic $O(N)$ programming procedure with no iterative optimization, enabling symbol-by-symbol updates when the chosen phase-control technology supports the required tuning speed. Using representative COTS components, we model the RF-front-end DC power of the proposed fully-analog transmitter and compare it against an equivalent COTS fully-digital array. For $N\le 16$, the comparison indicates significant RF-front-end power savings for the fully-analog architecture. The results in this paper are intended as a proof-of-concept for a narrowband fully-analog transmitter.

Problem

• fully-analog transmitter
• multi-antenna
• narrowband
• complex excitation synthesis
• unitary state preparation

Innovation

• fully-analog transmitter
• unitary state preparation
• programmable interferometric network
• phase-control elements
• power-efficient beamforming