DELAY PRIORITIES ENHANCE UTILIZATION OF ATM PON ACCESS SYSTEMS

A dominant factor for the widespread penetration and success of B-ISDN is the access cost for the low traffic customers. For residential and small business customers, the tree Passive Optical Networks (PONs) ar e a promising solution for the concentration of ATM traffic. Such a so lution however requires a method to arbitrate the access to the common Line Termination using the shared slotted system created on the PON t ree. The Medium Access Control (MAC) protocol presented in this work e mploys delay priorities to achieve more efficient multiplexing with be tter jitter performance in the multi-service B-ISDN environment. It re spects the demanding traffic control and enforcement methods of ATM wh ich do not tolerate certain traffic profile distortions. It avoids cel l clustering which deteriorates policing efficacy and link utilisation It shields time-constrained services from the adverse effect on their traffic profile of the contention from bursty services so that they s ee a very low offered load. The delay insensitive ABR cells are buffer ed and filled-in when traffic conditions allow on a best-effort basis. This results in a more intelligent multiplexing and smoother traffic stream at the exit. Thus a higher loading is possible for the same per formance leading to 'amortisation' of the additional complexity due to prioritisation. (C) 1997 Elsevier Science B.V.