Combining frequency-division and code-division multiplexing in a high-capacity optical network

Abstract

The combination of frequency division and code division multiplexing in a multiaccess network such that the beneficial aspects of each technique mitigate the shortcomings of the other is addressed. The feasibility and expected performance of the resulting hybrid network are examined. CDMA (code-division multiple access) is used to eliminate the need for laser frequency control, which is required for pure FDMA (frequency-division multiaccess) schemes. On the other hand, an FDMA-like mutual avoidance scheme exploits the limited tunability available to keep signals away from one another as much as possible, relieving the need for CDMA to protect against more than the occasional crossover of one interfering signal. This significantly limits the amount of spectral spreading required. The use of the hybrid network for high-bit-rate and low-bit-rate applications is discussed. The power budget for a local network utilizing a star coupler is outlined. >