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									                       MS EE Scholarly Paper Presentation

Dynamic Bandwidth Allocation using IPACT in

                                      Prerna Arora

                                Advisor: Dr. Brian Mark

                             Wednesday, August 8th, 2007
                                S&T II, Room 230A


      EPON i.e. Ethernet Passive Optical Networks is a technology that transmits data in
the form of Ethernet frames over Fiber-Optic medium. These are point-to-multipoint
networks i.e. a combination of both, shared as well as point-to-point networks which are
increasingly being used due to demand for higher bandwidth. EPON consists of a single
OLT (Optical Line Terminal) and several ONUs (Optical Network Units) which in turn
are connected to various end-users. The downstream transmission is broadcast to all the
ONUs and is selectively absorbed by the destination ONU and ignored by the others,
whereas in upstream transmission each ONU sends packets for the OLT. Thus, to avoid
collision of frames from the ONUs when they transmit at the same time, each ONU
should transmit in a particular timeslot, i.e. Bandwidth has to be allocated to each ONU.
The static TDM scheme where every ONU receives a fixed time slot to transmit, though
very simple, has the drawback that Statistical Multiplexing between the ONUs is not
possible. Due to the burstiness of traffic, some timeslots overflow while as other remain
underutilized. This results in the PON Bandwidth being underutilized. A dynamic scheme
which reduces the timeslot size when there is no data to send, would allow the excess
bandwidth to be used by the busy ONUs.
      Thus, in this paper, the performance of various Grant scheduling services based on
the IPACT method used in the Dynamic Bandwidth Allocation (DBA) algorithm for
EPON are discussed.

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