Constructing optical LIFO buffers of size B with 3 log2 B fiber delay lines

The lack of optical buffer is still one of the main problems that hinder the development of all optical network. The current works on this topic mainly focus on emulating optical buffers with fiber delay line (FDL). Recent advances have shown the feasibility of emulating many kinds of optical buffers, such as the First In First Out (FIFO) buffer, priority buffer, etc. The Last In First Out (LIFO) buffer is another important network components that can be used for providing QoS guarantee and congestion control. Huang et al. introduced a recursive construction of LIFO buffer with buffer size B by using no less than 9 log₂ B FDLs. In this paper, we try to reduce the number of required delay lines there. We will show that by combining every 3 fiber delay lines into one group and applying exponential growth of FDLs among groups, one needs only 3 log₂ B delay lines to emulate a LIFO buffers of size B.