Modeling, Analysis, and Design of Subcarrier Multiplexing on Multimode Fiber

This dissertation focuses on the use of subcarrier multiplexing (SCM) in multimode fibers, utilizing carrier frequencies above what is generally utilized for multimode fiber transmission, to achieve high bit rates. In the high frequency region (i.e., frequencies larger than the intermodal bandwidth), the magnitude response of multimode fiber does not decrease monotonically as a function of the frequency but is shown to become relatively flat (but with several deep nulls) with an amplitude below that at DC. The statistical properties of this frequency response at high frequencies are analyzed. The probability density function of the magnitude response at high frequencies is found to be a Rayleigh density function. The average amplitude in this high frequency region does not depend on the frequency but depends on the number of modes supported by the fiber. To transmit a high bit rate signal over the multimode fiber, subcarrier multiplexing is adopted. The performance of the SCM multimode fiber system is presented. The performance of the SCM system is significantly degraded if there are some subcarriers located at the deep nulls of the fiber. Equalization and spread spectrum techniques are investigated but are shown to be not effective in combating the effects of these nulls. To cancel the effects of these deep nulls, training process and diversity coding are considered. The basic theory of diversity coding is given. It is found that the performances of the system with training process and the system with diversity coding are almost identical. However, diversity coding is more appropriate since it requires less system complexity. Finally, the practical limits and capacity of the SCM multimode fiber system are investigated. It is shown that a signal with a bit rate of 1.45 Gbps can be transmitted over a distance up to 5 km.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2003

Author dc:creator

• Kanprachar, Surachet

Chair dc:contributor.committeechair

• Jacobs, Ira

Committee members dc:contributor.committeemember

• Stolen, Roger Hall
• Pratt, Timothy J.
• Shaw, John Kenneth
• Wang, Anbo

• Multimode Fibers
• Subcarrier Multiplexing (SCM)
• Training Process
• Optical Fiber Transmission
• Diversity Coding

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-04102003-143201

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/26744