| Popis: |
SuperPONs are access systems based on optical tree infrastructure. They are an extension of APONs (ATM-based passive optical networks), from which they differ mostly by their size. This paper considers the applicability of APON medium access protocols in the SuperPON context. More specifically, a modified version of the APON protocol proposed in Stojanovski and Gagnaire (1997, 1998) is considered. The underlying bandwidth allocation approach is of a hybrid type: CBR/VBR traffic is handled with per-block reservations, whereas ABR traffic is handled with per-cell reservations. Compared to APONs, SuperPONs cover a much larger area and serve a greater amount of end-users. This is why polling techniques similar to those in APON systems cannot be directly reused. In order to solve this problem we propose to associate the single pulse polling (SPP) proposed in Angelopoulos et al. (1996) with ABT-like (ATM block transfer) resource management cells. That is the main contribution of this paper. The performances of the proposed mechanism (notably the access delay and the delay variation) are evaluated by means of simulations. First simulation results show that this approach may be a viable solution for efficient traffic management over SuperPONs. Support for ABT/DT, ABT/IT and UBR transfer capabilities is also discussed. |
