10-04-2012, 01:42 PM
Optical CDMA
op_cdma.ppt (Size: 497 KB / Downloads: 201)
History Overview (CDMA)
1938, in the field of radar systems, examples of frequency hopping signal patterns were patented
During and after WWII the fact of BW expansion without pulse narrowing could also provide finer time resolution.
Introduction
CDMA used extensively in radio frequency communication systems, especially in 2G and 3G cellular telephone networks.
Basic Advantage is the way it handles a finite BW among a large number of users (more users can transmit the same data over the same Bandwidth)
Drawbacks DWDM
Dispersion
Attenuation
Four wave mixing
Non-linear nature of refractive index of optical fiber
comparison
Optical CDMA does not need time and frequency management because all the users transmit using the whole BW at the same time!
It can also operate asynchronously (as in wireless applications) without packet collisions.
Slot allocation requirements are not needed here in contradiction to TDMA and WDMA