FOCUS

Free-Space Optical Systems for Next Generation Communication Networks

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 Obiettivo del progetto (Objective)

'Free-space optical (FSO) communication is a license-free access technology with high-bandwidth capacity. It is a powerful alternative and/or complementary solution to commonly deployed fiber optic and wireless radio-frequency links. FSO is appealing for a number of applications including metropolitan area network extensions, enterprise/campus network connectivity, fiber back-up, back-haul for wireless cellular networks, disaster recovery, and quantum key distribution among others. Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing performance for long-range links. The major performance limiting factor for FSO links with ranges longer than one kilometer is the atmospheric turbulence-induced fading. Building upon the concept of cooperative diversity, the proposed research will devise efficient physical layer solutions tailored for the inherent characteristics of the FSO channel that remedy the shortcomings of existing systems. The proposed systems and techniques will provide a novel research framework on the design and analysis of relay-assisted (cooperative) FSO transmission. The results of this proposed research will be instrumental in the building of long-range, highly reliable, and ultra-fast FSO systems to meet the demanding requirements of next generation communication networks. This proposal is in fact a natural continuation of the applicant Dr. Uysal’s internationally renowned research program on FSO communication which he has carried out at the University of Waterloo in Canada. The Marie Curie International Reintegration Grant, if funded, will help Dr. Uysal transfer this internationally visible research program to Europe.'

Introduzione (Teaser)

An EU team explored the concept of cooperative transmission in free-space optical (FSO) networks. They reported significant performance improvements verified through extensive simulation studies.

Descrizione progetto (Article)

FSO is a licence-free optical wireless networking technology, having numerous advantages over conventional radio frequency systems. Nevertheless, atmospheric effects cause performance losses over link distances greater than 1 km.

The EU-funded 'Free-space optical systems for next generation communication networks' (FOCUS) project studied cooperative (relay-assisted) FSO for long range links. The work aimed to address FSO performance shortcomings using efficient physical layer solutions tailored to the characteristics of particular FSO channels. Turkey's Ozyegin University administered the project between September 2010 and August 2014.

Research into relay-assisted FSO systems with intensity modulation/direct detection (IM/DD) yielded various relaying architectures. The team investigated the fundamental performance bounds of proposed relay-assisted systems using tools from communication and information theories and demonstrated significant performance gains through relaying. The project also produced optimal relay placement strategies for additional performance improvements.

The EU team further studied coherent FSO systems which are more difficult to implement in practice, but provide more flexibility and further performance enhancements with respect to IM/DD counterparts. Finally, the team proposed and analysed a relay-assisted quantum key distribution scheme, which improves performance over long distances.

Overall, the FOCUS project helped to overcome limitations of FSO systems. The performance improvements helped with development of reliable, fast and secure long-range FSO communication systems.