Programmable Active Mirror: A Scalable Decentralized Router

Fikes, Austin; Khial, Parham P.; Nooshabadi, Samir; Hajimiri, Ali

doi:10.1109/tmtt.2020.3042516

Cited by 11 publications

(15 citation statements)

References 21 publications

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Section: Decentralized Relay System Considerationsmentioning

confidence: 99%

“…Detailed system-level analysis of scalable relays and their branches was performed in [8]. While the overall effective gain is not substantially different than a centralized relay, the behavior of a decentralized relay for signals coming from directions other than the intended receive direction is more complex [8]. While these signals do not interfere with the primary relaying function, they may be re-transmitted in an entirely new direction depending strongly on the branch locations and delay settings.…”

Section: Decentralized Relay System Considerationsmentioning

confidence: 99%

“…Furthermore, excepting RF-combining systems that struggle to implement programmable time delay, 1 the elements must also share a timing reference. The scalable relay [first proposed and demonstrated in [8] and shown in Fig. 1(d)] is a decentralized relay array architecture, which enables spatially separated elements with no shared timing reference to perform coherent beamforming.…”

mentioning

confidence: 99%

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A 28-GHz, Multi-Beam, Decentralized Relay Array

Nooshabadi

Khial

Fikes

et al. 2023

IEEE J. Solid-State Circuits

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Multi-beam relays can be used to overcome the non-line-of-sight (NLOS) issues in millimeter-wave (mm-wave) communication networks that serve many users in an obstruction-rich environment. We demonstrate a modular multi-beam relay array at 28 GHz, which is scalable and fully decentralized. The individual branches of the array are independent and do not need to share a timing reference or be physically located on the same substrate. Multi-beam capability is facilitated by a multi-channel baseband signal conditioning chain that includes a reconfigurable, passive, inductorless, 3rd-order N-path filter with programmable frequency-independent phase shift. This baseband signal conditioning chain enables beams concurrently multiplexed in spatial and frequency domains. We present the theory, design, and operation of the custom RFIC, which enables independent multi-beam relaying. Multiple RFICs are used to create relay arrays. A four-element relay array demonstrates three independently steered beams that utilize the full array aperture with a total wireless throughput of 625 Mb/s.

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Section: Decentralized Relay System Considerationsmentioning

confidence: 99%

Section: Decentralized Relay System Considerationsmentioning

confidence: 99%

mentioning

confidence: 99%

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A 28-GHz, Multi-Beam, Decentralized Relay Array

Nooshabadi

Khial

Fikes

et al. 2023

IEEE J. Solid-State Circuits

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“…Unfortunately, the performance of electrically large phased RIS in terms of bandwidth is well-known to be mediocre since temporal processing is limited [23]. Therefore, deployment of configurable thin but large surfaces in wireless communications is challenging and techniques for wideband adaptive operation with true-delay elements tend to be very sophisticated and lead to larger physical thickness [23] or require analog baseband processing with switched capacitor circuits [24]. More precisely, assuming a phased RIS implementation without using true-delay elements, the symbol duration must be greater than the propagation delay differences across the length of the array [25], leading to the following limitation on the fractional bandwidth…”

Section: A Ris Size Requirement and The Bandwidth Dilemma For Phase C...mentioning

confidence: 99%

“…These problems may be manageable for RedRIS configuration with 2D beamforming, particularly when using distributed amplification to offset switching insertion losses. However, 3D redirective RIS implementation is likely to be highly challenging and eventually, a hybrid approach combining both phased and lens-based RIS types would be meaningful [24], trading the wavefront selectivity for scalability. Such a salable hybrid implementation is shown in Fig.…”

Section: E Redirective Ris As a Key Enabler For Multifunctional Wave ...mentioning

confidence: 99%

Nonlocal Reconfigurable Intelligent Surfaces for Wireless Communication: Modeling and Physical Layer Aspects

Mezghani¹,

Bellili²,

Hossain³

2022

Preprint

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Delivering wireless ultrahigh-speed access at wider coverage is becoming considerably challenging due to the prohibitive investment costs per user and the necessary shift to range-limited millimeter-wave (mmWave) transmissions. Reconfigurable intelligent surfaces (RIS) are expected to extend the reach of mmWave and TeraHz signals more cost-effectively in situations where fiber backhaul and fronthaul are not accessible or infrastructure densification is costly. This paper investigates some challenges facing this technology, particularly in terms of scalability and the question of what type of RIS configurations would be appropriate for mmWave networks and what design strategies can be adopted to optimize the performance and minimize the signaling overhead. We conclude that RIS configurations for the wireless infrastructure likely need to be nonlocal (i.e., redirective, wavefront-selective) rather than local (i.e., reflective) to support communications and networking tasks such as integrated fronthaul and access (IFA) most efficiently.

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