Burst-to-Continuous Mode Converter for PON Speed
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Solution Overview
Problem
Conventional Ethernet Passive Optical Networks face challenges in high-speed burst mode Serializer/Deserializer operations due to constant charging and discharging of AC coupling capacitors, leading to time delays and limited speeds, typically operating at 1.25 GHz instead of the required 10 GHz.
Innovation Solution
A burst-to-continuous mode converter is introduced, comprising a burst mode Serializer/Deserializer and a continuous mode Serializer/Deserializer, which anticipates the arrival of upstream traffic by decrypting downstream GATE messages to extract start times, allowing for rapid clock and data recovery and conversion of bursty signals to continuous signals, enabling the use of standard high-speed components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If burst mode SerDes is used for upstream transmission, then data can be transmitted in short periodic bursts from ONUs to OLT, but constant charging and discharging of AC coupling capacitors causes time delays and limits operating speed to 1.25 GHz
Solution Approach 1:
The system segments the upstream transmission function into two parts: ONUs continue to transmit in burst mode, while a separate burst-to-continuous mode converter handles the conversion to continuous mode signals for the OLT. This segmentation allows each component to operate in its optimal mode without compromising the other.
Solution Approach 2:
A burst-to-continuous mode converter is introduced as an intermediary device between the ONUs and the OLT. This converter receives burst mode signals from ONUs, converts them to continuous mode signals, and transmits them to the OLT, thereby eliminating the harmful effects of burst mode on the OLT's AC coupling capacitors while preserving upstream data transmission capability.
2Productivity
If burst mode transmission is used, then upstream data can be sent in short periodic bursts, but AC coupling capacitors at the OLT constantly charge and discharge causing time delays in the data stream
Solution Approach 1:
The burst-to-continuous mode converter acts as an intermediary that absorbs and smooths out the bursty nature of upstream transmissions. By converting burst mode signals to continuous mode signals, it prevents the constant charging and discharging of AC coupling capacitors at the OLT, thereby eliminating time delays in the data stream while maintaining upstream data transmission productivity.
Solution Approach 2:
The converter performs preliminary action by converting burst mode signals to continuous mode signals before they reach the OLT. This pre-conversion prevents the problematic charging and discharging cycles from occurring at the OLT, thereby preventing time delays before they can affect the data stream.
3Speed
If standard high-speed components are used at the OLT, then continuous mode operation at 10 GHz is possible, but burst mode operation from ONUs causes capacitor charging/discharging issues
Solution Approach 1:
The system segments the transmission modes: ONUs operate in burst mode while the burst-to-continuous mode converter and OLT operate in continuous mode. This allows the OLT to use standard high-speed continuous mode components operating at 10 GHz without being affected by burst mode issues, thereby achieving both high speed and reliable operation.
Solution Approach 2:
The burst-to-continuous mode converter serves as an intermediary that shields the OLT from burst mode signals. It converts incoming burst mode signals from ONUs into continuous mode signals that are compatible with standard high-speed OLT components, enabling reliable 10 GHz operation without the reliability issues caused by burst mode capacitor charging and discharging.
Data Source
AI summary
A system to convert upstream burst mode data into continuous mode data in a passive optical network (PON) is provided herein. The system includes a burst mode Serializer/Deserializer (SerDes) that recovers a clock and burst mode data from an Optical Network Unit (ONU). The burst mode unit recovers the burst mode data based on a start time of burst mode data transmission by the ONU and a round-trip time between the ONU and an Optical Line Terminal (OLT). The system further includes a continuous mode SerDes that is coupled to the burst mode SerDes. The continuous mode SerDes is configured to receive the recovered clock and recovered burst mode data from the burst mode SerDes and convert the burst mode data into continuous mode data by buffering and padding the burst mode data based on the recovered clock. The continuous mode Serdes is configured to transmit the continuous mode data to the OLT.