Fine-grained function deployment and routing of RAN slicing with function reuse scheme in metro-aggregation elastic optical networks

The same function type from different service requests can be mapped to the same instance activated in a processing pool, i.e., the reuse of existing functions for resource-efficient deployment. However, this inevitably increases processing delays due to competition for instances, leading to longer transport delays. Consequently, a crucial challenge is how to coordinate function reuse and transport delay to maximize resource utilization while satisfying the delay requirements of each service. In this paper, we investigate the fine-grained function deployment and routing of radio access network (RAN) slicing with a function reuse scheme in metro-aggregation elastic optical networks (EONs). We first formulate the problem as an integer linear programming (ILP) model to find an exact solution. The main objective of the ILP model is to jointly minimize computing and bandwidth resource consumption to achieve optimal RAN deployment. Then, to overcome the non-scalability of the ILP model, we propose the longest common subsequence-based algorithm to obtain a near-optimal solution. Finally, extensive numerical results demonstrate that the proposed algorithm achieves high utilization of computing and bandwidth resources while satisfying the delay requirements of each RAN service request.