Processing efficient frame structure for passive optical network (PON)

The time division multiplexed (TDM) based passive optical networks like GPON/XGPON and EPON/10G-EPON use broadcast mechanism for downstream (DS) communication. This results in any DS frame being received and processed by all optical network units (ONUs), leading to significant processing energy wastage. Specifically, the ITU compliant PONs (GPON/XGPON) frame structure further aggravates this problem due to its inefficient frame structure and synchronous nature which requires sending of DS frames every 125 mu s. This frame structure requires an ONU to completely process every DS frame completely, even if it is not destined for it. The bit interleaved PON (Bi-PON) resolves this problem by changing the frame structure to a bit interleaved pattern and introduce a decimator unit that enables an ONU to tune to its concerned bits only. However, due to additional hardware requirement, this solution is not applicable to current ONU architecture. Consequently, this study presents a processing efficient version of GPON frame that helps an ONU to identify an unrelated DS frame at its start and thus discard it without complete processing. A processing efficient strategy for the medium access layer (MAC) processor of an ONU is also presented. The simulation results show a processing energy saving of 88%, 89% and 89.47% with proposed frame structure for a split ratio of 16, 32 and 64 respectively.