Abstract
Elastic optical network is a promising technology for building flexible and wideband communication systems. This technology features the frequency slot unit (FSU) concept, which defines the bandwidth unit in the frequency domain. The utilization of a specified number of consecutive FSUs allows the bandwidth to be flexibly assigned to a data stream. For a successful elastic optical network operation, the use of nonblocking optical switching networks is indispensable. This paper focuses on two previously proposed W-S-W switching network architectures, namely, WSW1 and WSW2. With regard to WSW1, a previous study elucidated that the hardware complexity, which is evaluated by the number of FSUs, decreases by employing the meta-slot scheme. A meta-slot is a frequency range containing one or more FSUs. Although its effectiveness depends on the sizes of meta-slot classes, the previous study did not present how to optimize the meta-slot class sizes. Moreover, the employment of meta-slots was not considered for WSW2 in the previous study. This paper investigates the optimization of meta-slot class sizes and demonstrates that such optimization is modeled as the shortest path problem. For WSW1, the meta-slot scheme optimized by the shortest path model is compared with the previously reported nonblocking conditions. The result confirms the superiority of the optimized meta-slot scheme. For WSW2, the assignment of meta-slots among S-switches is also essential. The paper models the assignment of meta-slots as a bin-packing problem. Thus, the near-optimal assignment can be obtained by a known bin-packing heuristic. For WSW2, the number of S-switches is evaluated for the optimized meta-slot scheme and the previously known nonblocking conditions. The result confirms that the meta-slot scheme is advantageous for WSW2 as well as for WSW1.
Highlights
Elastic optical network [1, 2] is a promising technology for building wideband and highly flexible communication networks
This paper focuses on the W-S-W configuration and its wide-sense nonblocking (WSNB) condition achieved by the meta-slot scheme proposed by Ohta [10]
The nonblocking criteria are categorized into the WSNB conditions for these methods since the frequency slot unit (FSU) set, or S-switch is selected for a newly requested connection from the group according to a specific rule
Summary
Elastic optical network [1, 2] is a promising technology for building wideband and highly flexible communication networks. A component of elastic optical switching networks is a bandwidth-variable wavelength selective switch (WSS) [1, 2] It can connect a data stream with any number of FSUs from a single input to any one of multiple outputs. For WSW1, this paper compares the number of FSUs among the WSNB condition by the meta-slot scheme optimized through the shortest path model, the SNB condition reported in [6], and the conventional WSNB condition by the algorithms reported in [9]. The optimal assignment of meta-slots among S-switches is investigated, and the meta-slot scheme is compared with the other nonblocking conditions previously known for WSW2.
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