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Optical Communications Systems – An Overview

Optical Communications Systems – An Overview. Xavier N. Fernando Ryerson University. Optical Communication Systems. Digital fiber optic (SONET) systems Microwave (analog) fiber optic (MFO) Systems Radio over fiber systems for wireless communications (ROF)

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Optical Communications Systems – An Overview

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  1. Optical Communications Systems – An Overview Xavier N. Fernando Ryerson University

  2. Optical Communication Systems • Digital fiber optic (SONET) systems • Microwave (analog) fiber optic (MFO) Systems • Radio over fiber systems for wireless communications (ROF) • Line of sight Infrared fixed wireless systems (Free Space Optics) • Diffused infrared indoor wireless systems

  3. Digital Fiber Optic Systems (SONET/SDH) High speed inter-city, intra-city, WAN type network with well defined standards and bit rates up 6.4 Tb/s (Nortel Networks OPTera 5000)

  4. Synchronous Optical Networks • SONET is the TDM optical network standard for North America (called SDH in the rest of the world) • We focus on the physical layer • STS-1, Synchronous Transport Signal consists of 810 bytes over 125 us • 27 bytes carry overhead information • Remaining 783 bytes: Synchronous Payload Envelope

  5. SONET/SDH Bit Rates

  6. Fig. 12-5: Basic STS-1 SONET frame STS-1 = 90 X 9 X 8 (bits)/(125 X 10-6) = 51.84 Mb/s

  7. Fig. 12-6: Basic STS-N SONET frame STS-N signal has a bit rate equal to N times 51.84Mb/s Ex: STS-3  155.52 Mb/s

  8. Microwave Fiber Optic (MFO) Analog Systems Conventionally used for CATV Distribution (Fiber-Coax Systems) and recently for multimedia delivery via high-speed internet cable modems

  9. Analog Systems • Modulating signal is analog (RF) • Several RF carriers can be transmitted over a single fiber in FDM manner called Sub Carrier Multiplexing • Each RF Carrier is an independent communication channel • Ex: CATV Systems • Linearity is the biggest concern

  10. Direct Analog Modulation LASER LED Nonlinear distortions (Saturation & Clipping) are the major concern

  11. Sub-Carrier Multiplexing

  12. Fiber-Coax Access Network Multiplexing analog and digital is possible in SCM

  13. Radio over Fiber (ROF) for Wireless Systems A subset of MFO systems – However, the microwave signal is transmitted into the free-space to give wireless access and mobility. Gives unique challenges.

  14. The Technology

  15. RT Fiber Distribution RAP RAP RAP Consistent High Data Rate Everywhere Dramatic Increase in Capacity !!

  16. Multi Standard Fiber-Wireless Central Base Station RAP RAP RAP Y Radio over Fiber (ROF) (Simple) Up/Down links Y 802.11 voice Y Single ROF link can support voice and data simultaneously Micro Cell

  17. Indoor Wireless Infrared Systems http://www.shu.ac.uk/ocr/downloads/owc-gen-00/ For short range, diffused type communications within a room or office space Extending the capabilities IrDA Indoor Wireless LANs Limited Mobility

  18. Scenario for WLANusing Infrared Radiations:

  19. Free Space Optic Systems http://www.freespaceoptic.com Outdoor point-to-point communication using a highly focused laser beam Eg: TereScope TS1  $5,035 USDTransmission rate 100 Mbps full duplex (Fast Ethernet) Operational range 100m to 380m (300-1250 feet)

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