Proposal of a simple CD roadm with contention-free add/drop function

We propose a simple configuration for colorless and directionless (CD) reconfigurable optical add/drop multiplexers that enables contention-free add/drop operation to be achieved. In the configuration, we apply a combination of multiple small-port-count CD add/drop banks (CD banks) and round-robin CD bank assignment. Evaluation results show that the proposed configuration can substantially reduce intra-node contention.