  Using Optical Orthogonal Frequency Multiplexing (O-OFDM), variable bandwidth
channels can be created in Elastic Optical Networks (EON). This allows the use
of spectrum more efficiently by allocating integral multiple of basic bandwidth
slots to the lightpath requests. Consequently, such networks are also called
flexible grid optical networks. It also adds a constraint of keeping all the
allocated slots together when deciding the routes for the requests. This
constraint called the contiguity constraint makes the routing and spectrum
algorithms more challenging. In any network, the lightpath requests will arrive
and depart dynamically and will invariably lead to spectrum fragmentation, and
hence network will have a reduction in maximum possible utilization due to
increased blocking probability. In this paper, we have presented an improvised
RSA algorithm that leads to lesser fragmentation. It is evident from the
results that the presented RSA algorithm uses adaptive parameters to reduce the
blocking probability and fragmentation compared to other algorithms reported in
the recent past.
