Research On Self-Adaptive Elastic Fiber Loop Optical Buffer In Optical Packet Switching Network

Optical packet switching (OPS) network can achieve higher data rates and better scalability by transmitting optical packets directly with minimized optical-electrical-optical (OEO) conversion. It is one of the promising solutions for future networks with the explosive growth of data, the diversified services and the packetized data flow. Among critical technologies that can accelerate the development of the OPS network, the optical packet buffer is the one who can not only solve the congestion problem, but also play key roles in procedures of optical label extraction, routing, packet synchronization, et al. The performance of optical buffer is of great significance on the development of the OPS network.This dissertation was based on the fiber delay line optical buffer with low cost and mature technology, focusing on the structure innovation and network performance analysis.First, based on the survey of current state of the art in optical buffers, two traditional buffer structures, the Feed-Forward (FF) and the Feed-Back (FB) structure, were analyzed in detail. By taking into account both features of traditional buffering structures and requirements of the future buffering capability, the concept of Buffer Flexibility was proposed. This new concept aimed at providing a unified network performance evaluation system, and took into consideration three restrictions simultaneously which have direct or indirect influences on optical network performances. They are the maximum buffering time restriction, the delay granularity restriction, and the packet length limitation.Second, a new elastic fiber loop optical packet buffer (E-FLOB) was proposed. The new structure makes a breakthrough of traditional structure by taking advantages of both the FF buffer and the FB buffer. Also, the mutual restraint among the three restrictions in the Buffer Flexibility is weakened, which is the essential reason for acquiring better buffering performance. Theoretical analyses demonstrated that the new structure has the advantages of both two traditional structures, such as the smaller physical size, the lower noise accumulation, and the higher link utilization.Last, the queuing model of the buffer in one output port with a single wavelength was established for the feed-forward buffer. The simulation platforms of the two traditional buffer structures and the new E-FLOB one were also established. Results indicated that the FB structure can only be used in networks with light load, yet the other two structures have better performances in networks with heavier load such asρ=0.8. In addition, the new elastic-loop structure has even better performances on packet loss probability when its physical size is half of the FF structure.