Simultaneous connections routing in W-S-W elastic optical switches with limited number of connection rates

The three-stage switching fabric of wavelength-space-wavelength architecture for elastic optical switches is considered in the paper. It serves connections which can occupy different spectrum width. The upper bound for rearrangeable condition for such switching fabric which serves a limited number of connection rates is derived and proved. The control algorithm based on matrix decomposition is also proposed. For the switching fabric of capacity 2×2 serving only two connection rates, necessary and sufficient conditions are derived and proved. The required number of frequency slot units in interstage links is much lower than in the strict-sense nonblocking switching fabrics.