Multi-Rate Upstream 10GEPON Using High-Efficiency PAM Coding
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Solution Overview
Problem
Existing 10GEPON systems do not cost-effectively accommodate evolving upstream and downstream bandwidth ratios, with 10/1 and 10/10 data rate combinations being either too costly or insufficient for supporting changing end-user applications, particularly in high split Fiber to the Home (FTTH) deployments.
Innovation Solution
A system that uses existing 1Gbps optics and high-efficiency coding schemes, such as pulse amplitude modulation (PAM) with multiple levels, to provide upstream data rates between 1Gbps and 10Gbps, allowing for flexible upstream/downstream bandwidth ratios and supporting high split FTTH deployments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 10Gbps upstream data rate is implemented in 10GEPON system, then bandwidth capacity is improved, but cost increases
Solution Approach 1:
The patent changes the modulation scheme parameter from traditional NRZ to high-order PAM (PAM-4, PAM-8, PAM-16) to achieve higher data rates. By changing the modulation order parameter, the system can provide upstream rates of 2.5Gbps, 5Gbps, 7.5Gbps, and 10Gbps using the same physical layer infrastructure, thus avoiding the need for expensive 10Gbps optics while still achieving high bandwidth capacity.
Solution Approach 2:
The patent makes the physical layer universal by designing a single PAM-based modulation scheme that can support multiple data rates (2.5Gbps, 5Gbps, 7.5Gbps, 10Gbps) and multiple upstream/downstream bandwidth ratios (10/1, 10/2.5, 10/5, 10/7.5, 10/10). This multi-functional approach allows the same hardware infrastructure to serve different service requirements without requiring separate dedicated systems for each rate, thereby reducing overall system cost.
2Device complexity
If fixed 10/1 or 10/10 data rate combinations are used, then system simplicity is maintained, but adaptability to changing bandwidth demands deteriorates
Solution Approach 1:
The patent introduces dynamic adaptability by allowing the system to switch between different PAM modulation orders (PAM-4, PAM-8, PAM-16) and different upstream/downstream bandwidth ratios based on real-time traffic conditions and service requirements. The system can dynamically adjust the modulation scheme to provide optimal performance for different applications, such as video conferencing, file transfer, or future services, without requiring physical reconfiguration or additional hardware.
Solution Approach 2:
The patent uses parameter changes in the modulation scheme to achieve flexibility. By changing the PAM order parameter and the upstream/downstream rate ratio parameter, the system can adapt to various bandwidth demands while maintaining the same physical layer infrastructure. This allows the system to evolve from fixed 10/1 or 10/10 configurations to dynamic multi-rate configurations that match actual user needs.
3Productivity
If high-order modulation schemes are used, then spectral efficiency is improved, but implementation complexity increases
Solution Approach 1:
The patent replaces complex high-order modulation implementation with a structured approach that builds upon well-understood PAM principles. Instead of implementing PAM-16 or higher directly, the system uses a hierarchy of PAM orders (PAM-4, PAM-8, PAM-16) that can be systematically implemented using standard digital signal processing techniques. The modulation scheme is integrated with existing PON protocols and can be configured through software, reducing the need for complex hardware redesign.
Solution Approach 2:
The patent incorporates feedback mechanisms where the ONU and OLT negotiate the appropriate PAM order and bandwidth ratio based on channel conditions and service requirements. This feedback-based adaptation allows the system to use high spectral efficiency modulation only when necessary and appropriate, avoiding the complexity of always operating at the highest modulation order. The feedback loop enables dynamic selection of the optimal modulation scheme based on real-time conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach lowers costs per subscriber by utilizing existing optics and provides adequate bandwidth for changing bandwidth demands, ensuring cost-effective and efficient data transmission in 10GEPON systems.
Implementation Method 1
an optical transmission device configured to transmit the encoded data to the OLT
Implementation Method 2
The second PHY includes: an avalanche photodiode; and an amplifier coupled to the avalanche photodiode
Data Source
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AI summary
Systems and methods are disclosed to provide an upstream rate between 1Gbps and 10Gbps in a cost effective manner in a 10GEPON. In an embodiment, an optical network unit (ONU) transmitter includes a burst transceiver and a physical layer (PHY) including a high performance digital to analog converter (DAC), a pulse amplitude modulation (PAM) module configured to encode end user data using a modulation scheme having more than two levels, and a laser. The ONU transmitter transmits the encoded end user data to an optical line terminal (OLT) receiver, which demodulates the data using a PAM demodulator and sends it to a service provider.