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# Analogue wireless beamforming exploiting the fiber-nonlinearity of radio over fiber based C-RANs

Li, Yichuan, Ghafoor, Salman, Katla, Satyanarayana, El-Hajjar, Mohammed and Hanzo, Lajos (2019) Analogue wireless beamforming exploiting the fiber-nonlinearity of radio over fiber based C-RANs. IEEE Transactions on Vehicular Technology.

Record type: Article

## Abstract

As a key technique of supporting the fixed backbone network, radio over fiber (RoF) systems transmit the radio frequency signals over optical fiber in order to take advantage of their large available bandwidth. In this context, optical fiber aided phased antenna array (PAA) based beamforming techniques have attracted substantial research interest with the goal of improving the cell-edge coverage of cellular base stations. In this paper, we conceive a novel optical fiber aided beamforming technique based on the fiber's nonlinearity to be applied in cloud radio access network (C-RAN). In our proposed technique, the PAA elements are fed by the phase-shifted signals introduced by our highly nonlinear fiber (HNLF) aided phase-shifting solution, which results in an angular beamsteering range of around 90$^{\circ}$. This can be exploited by sectorization in cellular networks to reduce the cochannel interference imposed. Furthermore, we exploit the proposed RoF-aided phase shifting technique in C-RAN, where our proposed system takes advantage of the centralized signal processing capability of the RoF system to conceive an all-optical processing based tunable beamforming system. While our flexible HNLF-aided phase-shifting process is confined to the central office of the C-RAN, the end users in the C-RAN cellular networks are capable of flexibly choosing the serving remote radio heads (RRHs) and employing diverse wireless transmission techniques. Through integrating our HNLF-aided phase-shifting design into the proposed C-RAN, we impose as little as 0.1 dB signal-to-noise Ratio (SNR) degradation compared to its traditional electronic counterpart, which requires extra phase-shifters.

Text
Fiber_Nonlinearity_based_all_optical - Accepted Manuscript

Accepted/In Press date: 11 January 2019
e-pub ahead of print date: 17 January 2019

## Identifiers

Local EPrints ID: 427640
URI: http://eprints.soton.ac.uk/id/eprint/427640
ISSN: 0018-9545
PURE UUID: 0d6b2628-fe6f-462c-89e4-44c64c7796a5
ORCID for Yichuan Li: orcid.org/0000-0003-2078-0983
ORCID for Satyanarayana Katla: orcid.org/0000-0002-5411-3962
ORCID for Mohammed El-Hajjar: orcid.org/0000-0002-7987-1401
ORCID for Lajos Hanzo: orcid.org/0000-0002-2636-5214

## Catalogue record

Date deposited: 24 Jan 2019 17:30

## Contributors

Author: Yichuan Li
Author: Salman Ghafoor
Author: Satyanarayana Katla
Author: Mohammed El-Hajjar
Author: Lajos Hanzo