Optimal planning and design of SRLG-aware survivable LR-PON for wireless and FTTx networks

Abstract

Protection to optical network units (ONUs) against failure of their distribution fibers (DFs) in a long-reach passive optical network (LR-PON) is highly desirable to provide uninterrupted internet services to the users. In practical network scenarios, DFs form shared-risk link groups (SRLGs). The existing SRLG-aware protection schemes depend on residual bandwidth of ONUs. Therefore, they are cost-inefficient and also fail to satisfy high reliability requirements (RRs). We for the first time propose a nonresidual bandwidth based partial protection scheme and related architecture to provide partial protection to ONUs against a single SRLG failure. Following the proposed scheme, we formulate an integer linear programming (ILP)-based optimization problem to provision backup DFs and network components for providing protection with the minimum protection cost. To meet the strict delay requirement for real-time applications, the proposed ILP model restricts the length of backup DFs to be employed to restore the traffic transmission. As the proposed ILP model becomes computationally intractable for large networks, we also propose a heuristic scheme that provides fairly close results to that of the ILP model. We assess the performance of the proposed partial protection scheme in terms of protection cost and total length of backup DFs (TLBDF). Through exhaustive simulation study we show that the proposed partial protection scheme not only satisfies high RRs but also requires much lower protection cost and TLBDF as compared to the existing SRLG-aware protection schemes.