OLT Codeword Grouping for ONU Decoding Complexity
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Solution Overview
Problem
High-speed passive optical networks require ONUs to decode and decapsulate data frames at full line rates, leading to increased complexity and energy consumption, as well as the need for costly upgrades to match the OLT's high data rate, which is inefficient and costly.
Innovation Solution
The OLT groups data units into subsets and encodes them into sets of codewords, interleaving them to maximize the time between codewords for each ONU, providing subset information to allow ONUs to decode only relevant codewords, reducing processing requirements and enabling energy savings or increased decoding iterations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ONUs decode and decapsulate data frames at full line rates, then data throughput is maintained, but device complexity and energy consumption increase
Solution Approach 1:
The patent segments the continuous stream of codewords into distinct groups, where each group contains codewords intended for specific ONUs. This segmentation allows ONUs to selectively decode only the groups containing their data, rather than decoding all codewords at full line rate, thereby reducing decoding complexity while maintaining overall data throughput.
Solution Approach 2:
The patent applies preliminary error correction encoding at the OLT before transmission, organizing codewords into groups with identifiers. This preliminary structuring enables ONUs to quickly identify and extract only their relevant codewords without performing full-rate decoding, reducing their processing complexity while preserving throughput.
2Speed
If ONUs operate at full line rate, then data rate requirements are met, but cost increases due to need for expensive upgrades
Solution Approach 1:
By segmenting codewords into identifiable groups and allowing ONUs to selectively decode only their assigned groups, the patent enables ONUs to operate at lower effective data rates while still meeting overall network throughput requirements. This reduces the need for expensive full-line-rate ONU upgrades.
Solution Approach 2:
The patent applies different processing requirements to different portions of the data stream - specifically, ONUs only need to process the local subset of codewords intended for them. This local quality approach allows ONUs to have reduced processing capabilities compared to full-line-rate requirements, lowering manufacturing costs.
3Reliability
If ONUs decode all codewords, then error correction is comprehensive, but energy consumption increases
Solution Approach 1:
The patent segments the codeword stream into groups with identifiers that allow ONUs to quickly identify which groups contain their data. ONUs can then enter low-power states during intervals when their groups are not being transmitted, significantly reducing energy consumption while maintaining comprehensive error correction for their specific data.
Solution Approach 2:
The patent implements periodic transmission of codeword groups with clear identifiers, allowing ONUs to periodically activate their decoders only when their assigned groups are being transmitted. This periodic operation mode reduces energy consumption compared to continuous full-rate decoding, while ensuring reliable error correction when needed.
Data Source
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AI summary
Example embodiments describe an optical line terminal, OLT, and a method therefor. According to example embodiments, the OLT comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the OLT to perform: grouping data units for the ONUs in groups, wherein a group comprises data units for a subset of the ONUs, encoding the groups of data units into respective sets of at least one codeword, interleaving the at least one codeword of the respective sets thereby obtaining a stream of codewords, and sequentially transmitting the stream of codewords to the ONUs. Other example embodiments relate to an optical network unit, ONU, and a method therefor.