Code division multiplexing lightwave networks based upon opticalcode conversion

摘要

Lightwave networks realized through code division multiple accessntechniques are extensively studied to determine their ultimatencapabilities. Here, these concepts are extended to networknimplementation by introducing an optical code division multiplexingn(OCDM) multihop strategy using optical coding. It is shown that thisnapproach is effective in scaling up existing wavelength divisionnmultiplexing (WDM) networks without a significant drain of thenwavelength resources. The concept of a virtual optical code path (VOCP)nis introduced within the transport layer of the network. It isndemonstrated that this is a potential solution to wavelength path (WP)nallocation problems which may plague WDM based transport networks of thenfuture. Crucial to the VOCP concept is optical code conversion. Theninterplay between this added functionality and the optical cross-connectnis highlighted; the optical cross-connect serves to establish VOCP/VWPn(virtual wavelength path) in the hybrid transport layer. An example ofnoptical code conversion is introduced. It is based on coherent OCDMnprinciples in which bipolar phase-shift keyed (PSK) optical pulsensequences are used as the signature codes. Error-free code conversionnusing a four-chip optical encoder/decoder is successfully performed atn1.24 Gbit/s. The results show the feasibility of high bit rate OCDMntransmission with optical code conversion