EPoC Time-Frequency Mapping for OFDMA Subcarrier Allocation
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Solution Overview
Problem
In Ethernet Passive Optical Network over Coax (EPoC) systems, there is a need for efficient time to time-frequency mapping and demapping, as well as upstream bit loading profile balancing, to support Orthogonal Frequency Division Multiple Access (OFDMA) effectively, due to differences in upstream access methods between the EPON and EPoC portions of the network, which leads to challenges in translating EPON upstream time grants to OFDMA resources and ensuring non-overlapping subcarrier usage among CNUs.
Innovation Solution
The implementation of systems and methods that translate EPON upstream time grants to OFDMA resources, synchronize upstream transmissions to align within the same OFDMA frame, and efficiently allocate subcarriers among multiple CNUs, using a PHY controller to determine bit loading profiles and map MAC bit streams to subcarriers, ensuring no overlapping subcarriers and optimal data transmission within defined OFDMA frame boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If EPON upstream time grants are translated to OFDMA resources, then data transmission efficiency is improved, but subcarrier allocation complexity increases
Solution Approach 1:
The patent segments the upstream transmission time grant into multiple discrete time slots, and segments the frequency spectrum into multiple subcarrier groups. Each CNU is allocated specific time slots and subcarrier groups, creating a structured grid that simplifies the mapping process from time-domain EPON grants to frequency-domain OFDMA resources while preventing subcarrier overlaps.
Solution Approach 2:
The patent introduces an intermediary mapping function that translates EPON time grants into OFDMA resource allocations. This intermediary layer handles the complexity of subcarrier allocation by providing a systematic translation mechanism that accounts for CNU-specific parameters such as propagation delay and bandwidth capabilities, thereby resolving the contradiction between transmission efficiency and allocation complexity.
2Quantity of substance
If multiple CNUs are allocated subcarriers in the same OFDMA frame, then data capacity is increased, but subcarrier overlap interference occurs
Solution Approach 1:
The patent applies local quality by allocating different subcarrier groups to different CNUs within the same OFDMA frame. Each CNU receives a unique subset of subcarriers tailored to its specific requirements and channel conditions. This localized allocation ensures that while multiple CNUs transmit simultaneously, their subcarrier assignments do not overlap, thereby increasing overall data capacity while preventing interference.
3Productivity
If upstream transmissions are synchronized to align within the same OFDMA frame, then time utilization is improved, but transmission timing precision requirements increase
Solution Approach 1:
The patent implements preliminary action by pre-calculating and pre-synchronizing the transmission timing for each CNU before the actual data transmission begins. The system determines the required timing adjustments based on each CNU's propagation delay and allocates time slots accordingly in advance. This preliminary synchronization ensures that all CNUs transmit their data within the same OFDMA frame boundaries, improving time utilization while managing timing precision requirements through advance planning.
Data Source
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AI summary
Embodiments include, but are not limited to, systems and methods for enabling Orthogonal Frequency Division Multiple Access (OFDMA) in the upstream in an Ethernet Passive Optical Network over Coax (EPoC) network. Embodiments include systems and methods for translating Ethernet Passive Optical Network (EPON) upstream time grants to OFDMA resources represented by individual subcarriers of an upstream OFDMA frame. In an embodiment, the translation of EPON upstream time grants to OFDMA resources ensures that Coaxial Network Units (CNUs) sharing an OFDMA frame do not use overlapping subcarriers within the frame. Embodiments further include systems and methods for timing upstream transmissions by the CNUs in order for the transmissions to be received within the same upstream OFDMA frame at a Fiber Coax Unit (FCU). Embodiments further include systems and methods for re-generating a data burst from OFDMA resources for transmission from the FCU to an Optical Line Terminal (OLT).