Reliability of FSO links in next generation optical networks

2008 10th Anniversary International Conference on Transparent Optical Networks

Loschnigg

Birnbacher

et al. 2008

Self Cite

In the last couple of years the need for higher data rates and more bandwidth has arisen. This development will continue in the next couple of decades and allegorizes a challenge for the future Next Generation Networks. Taking this into account the end-user will need higher data rates, getting theoretical access to the full available bandwidth of the backbone delivered to the home.Free Space Optics (FSO) is an excellent supplement to conventional radio links and fiber optics, capable of handling point-to-point and point-to-multipoint connections. On the one hand-side FSO is a broadband wireless solution for the "Last Mile" connectivity in metropolitan networks, on the other hand-side FSO can be used to interlink locations within one local area network. In the last years different types of cost-effective systems were developed and realized at the Institute of Broadband Communication of Graz University of Technology (TU Graz). The first type was based on a modular concept using available standard components allowing demonstrations at a data rate of 2 × 10 Mbit/s for short distances up to 300 m at a specific power margin of 25 dB/km. Later the units were improved to allow a data rate of 100 Mbit/s, higher data rates are currently under development.The reliability and availability of a FSO-link is mainly determined by the local atmospheric conditions, in free space the transmitted light is reflected, refracted or absorbed by objects, rain, fog, wind or sun. All these parameters directly influence the quality of a FSO-link and indirectly affect the quality of an Access Network.Many FSO-installations (permanent and nomadic use) have been set-up in the area of Styria by TU Graz and cooperation partners. In this contribution we will show some practical installations for different events, including the latest permanent installation, which was started in the summer of 2007 together with the municipality of Dobl, a small suburb of Graz, and the ML11 GmbH, an IT-company. Within this cooperation the elementary school of Dobl was connected to the Internet via FSO. The FSO-units were successfully installed and the setup is now used to explore the influence of weather on the FSO-link in the area of Graz. INTRODUCTIONToday, many people need high data rates for Internet or network access. Therefore Free Space Optics (FSO) is a well suited technology. The high bandwidth of the "Backbone" (fiber network) is also available for the enduser. The research group for Optical Communication ("OptiKom") at the Institute of Broadband Communication, TU Graz, has done research in the field of Free Space Optics (FSO) over a period of near 15 years. The work includes the development of FSO-equipment for research purpose and the evaluation of commercially available FSO systems for the climate in Graz (Austria) in co-operation with industrial partners. The main projects in this field have been funded by Telekom Austria AG, InfraServ Gendorf and the Government of Styria. Additional experiments and investigations in this field were started within the...

Section: Temporary Use Within Folk-festival "Aufsteirern"mentioning

confidence: 99%

High reliable optical wireless links for the last mile access

2008 10th Anniversary International Conference on Transparent Optical Networks

Loschnigg

Birnbacher

et al. 2008

Self Cite

“…Mainly the weather conditions influence the optical beam [1]. Rain causes a small attenuation of approximately 3 dB/km [1], because raindrops size is not comparable to the operating optical wavelengths and so they don't scatter the laser energy. However, dense fog attenuates the optical transmission power drastically.…”

Section: Introductionmentioning

confidence: 99%

Integration of FSO in local area networks - Combination of Optical Wireless with WLAN and DVB-T for last mile internet connections

2014 19th European Conference on Networks and Optical Communications - (NOC)

Plank

Pezzei

et al. 2014

Nowadays FSO (Free Space Optics) also called Optical Wireless, is a well-established technology for closing the last mile gap. Optical Wireless is best suited to be directly connected to fibre optics, like the extension of a fibre cable for access networks. But also combinations with RF-and wireless networks are of main interest in current applications. Various technologies have different influences on weather conditions, because of the used wavelengths (frequencies) and the differences in the propagation behaviour and the transmission channel. This contribution will show at first the selection of best suited wavelengths for optical wireless communications (OWC) for the last mile access in relevance to the weather effects and the influences of beam divergence and beam shaping. The second part is showing the usage of FSO in combination with other wireless technologies (as a special scenario with WLAN and DVB-T), available for regions of low Internet coverage. FSOallows a broadband access with high data rate for users not connected so far by fibre cables. It is a well-known fact that peripheral regions lack of reasonable broadband Internet services. WLAN and FSO are license-free transmission technologies and DVB-T has become a geographically widespread technology. This paper will show an alternative Internet access method using WLAN and FSO systems as a data uplink and DVB-T as a downlink channel for broadband data access. The work was carried out within international cooperations in the frame of a special programme of European Union called SEE (South-East-Europe)

“…1550 m) are the preferred option. FSO links through the troposphere are mainly influenced by weather conditions [2]. Rain does not influence optical transmissions drastically (attenuation of 3 dB/km), because raindrops size is a few millimetres much large than the operating optical wavelengths (1550 nm), thus causing minimal scattering of the laser energy.…”

Section: Principles On Free-space Optics and Experimentsmentioning

confidence: 99%

“…Additionally, some recent major performance improvement results (using hybrid systems and specific modulation and coding schemes) are presented. The main focus is the reliability of optical components and devices in communication networks and systems One of the big points is to increase the channel capacity, reliability and availability of FSO links and its combination with microwave links [2] important for the "next generation" future networks.…”

Section: Improvementsmentioning

confidence: 99%

Analysis and evaluation of optimum wavelengths for free-space optical transceivers

2010 12th International Conference on Transparent Optical Networks

Plank

Awan

et al. 2010

Self Cite

The objective of this paper is to analyse and present the latest results obtained for free-space optics (FSO) within the EU COST Action IC-0802 and within the European Space Agency (ESA) contract. First, the FSO technology is briefly discussed and some performance evaluation criteria for FSO are provided. Some optical signal propagation experiments through the atmosphere (including the recent investigations in airborne and satellite application for FSO) are also shown. In the main part, considerations on suitability of different optical wavelengths are brought into question. The wavelength selection is dependent on the atmospheric effects and on the availability of receiver and transmitter components. Discussion on the available receiver(s) and transmitter(s) includes the focus on advantages and mainly the costs of the different systems. In the final part, we examine the latest practical results (carried out within the COST Action IC-0802) on modelling of the FSO channel under fog conditions and other atmospheric effects. Additionally, recent results, showing major performance improvement, based on the hybrid system and specific modulation and coding schemes are presented. Keywords: Free-space optics, broadband wireless, network architectures, last mile access, reliability and availability. INTRODUCTIONFSO communication systems consist of an optical transmitter which is a laser source or a LED, a modulator and a telescope. The receiver consists of a detector, a decoder and a telescope to collect the optical signal. The optical signal propagates through the free space which acts as the link channel. Interest in FSO continues to grow mainly for two reasons: first identification as an attractive alternative or a complementary to existing microwave (millimetre wave (MMW)) and the radio frequency (RF) communication links, and secondly being a broadband wireless solution for the "Last Mile" connectivity in metropolitan networks, point-to-point and point-tomultipoint link configurations. Last couple of years have witnessed a growing demand for higher data rates and wider bandwidths from the end user to manipulate multimedia information. This development will continue in the next couple of decades being a challenge for the future Next Generation Networks. So the end-user will need higher data rates and access to the fully available bandwidth within the backbone delivered to the home. Currently FSO is being researched for applications involving ground-to-ground (short and long distance terrestrial links), satellite uplink/downlink, inter-satellite, deep space probes to ground, and ground-to-air/air-toground terminal (UAV, HAP etc.) [1]. This has resulted in some successful experiments such as SILEX (a link between Artemis and SPOT-4). The prime advantages of FSO are: higher data rates exceeding easily 100 bit/s using wavelength division multiplexing (WDM) techniques, security aspects, EMC/EMI immunity and frequency regulation issues. Additionally, small terminal size, light weight, minimal aperture sizes and low ...