| Popis: |
A new generation of access networks is necessary for the provision of broadband services. ATM Passive Optical Networks (APON) are considered as a promising alternative among other numerous technologies based either on copper pairs, coaxial cables or wireless infrastructures. An APON is a point-to-multipoint broadcast system in the downstream direction and a multipoint-to-point shared medium in the upstream direction. A Medium Access Control (MAC) protocol has to be used for the upstream traffic in order to arbitrate concurrent access. The aim of this paper is first to describe the APON system architecture and the physical layer frame format as standardized by ITU-T in the G.983 recommendation. We then propose a possible approach for traffic management over such systems considering three aspects: MAC protocols, service disciplines and buffer management. Two types of traffic are considered, stream and elastic. Stream traffic refers to flows generated by real-time applications such as voice or video, whereas elastic traffic refers to TCP/IP flows. In the last part of our paper, we evaluate the performance of this approach by means of computer simulations. |
