WDMA/subcarrier-FDMA lightwave networks: limitations due to opticalbeat interference

The authors present a general model of optical beat interference, and its contribution of channel outage in a WD-SFDMA (wavelength division-subcarrier frequency division multiple access) network. The probability of channel outage due to optical beat interference is determined from analysis and computer simulation for externally and directly modulated single-mode lasers. These results are used to calculate the ultimate limitation on the throughput and capacity of the network due to beat note interference, for a simple retransmission protocol. It is shown that, as more subcarrier channels are added, network capacity increases sublinearly and eventually saturates