New upper bound for a rearrangeable non-blocking WSW architecture

An optical network based on elastic optical switches allows requests using different spectrum widths to improve utilisation efficiency. This study considers one three-stage WSW (waveband switching-space switching-waveband switching), optical node architecture for elastic optical networks. A sufficient condition for a rearrangeable non-blocking WSW architecture with limited input/output links has been derived in an earlier work. In this study, the author improves the upper bound by adopting a new interstage link partition scheme associated with a tricky routing algorithm. Suppose a WSW architecture has r input/output links each of which has n frequency slot units (FSUs). Compared with earlier results, the results of the proposed scheme show that s - 1 (or 3s - 4) FSUs per interstage link can be reduced for even (or odd) min{r, n}, where s = min{ left ceiling r/2 right ceiling , left ceiling n/2 right ceiling }. The reduction gain is at least 3.5% (or 10%) for even (or odd) min{r, n} if r = n <= 26, even achieving 23.3% for limited odd r = n.