Optical Line Terminal Wavelength Multiplexing for Low Latency PON
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Solution Overview
Problem
Current TDM-PON systems used in FITH scenarios experience high latency and jitter due to time division multiplexing in both uplink and downlink directions, making them unsuitable for new service scenarios requiring low latency and high reliability.
Innovation Solution
The proposed optical communications system includes an optical line terminal (OLT) with an electrical multiplexing module, optical modulators, and uplink optical receivers, which multiplex downlink data frames into a high-speed bit stream and modulate it into a dedicated wavelength, allowing each user to perform point-to-point data transmission. This design reduces the need for tunable filters, lowers wavelength resource requirements, and improves system reliability by using distinct wavelengths for uplink signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time division multiplexing is used in both uplink and downlink directions, then bandwidth aggregation and convergence are achieved, but latency and jitter increase
Solution Approach 1:
The patent segments the multiplexing approach by applying different schemes to uplink and downlink directions. Downlink uses time division multiplexing with a single wavelength, while uplink uses wavelength division multiplexing with multiple wavelengths, thereby reducing latency and jitter in uplink transmission while maintaining bandwidth aggregation capability
Solution Approach 2:
The patent introduces wavelength as an additional dimension for multiplexing in the uplink direction. Instead of solely using time division multiplexing, it combines time division with wavelength division, allowing multiple uplink signals to transmit simultaneously on different wavelengths, thus reducing latency and jitter
2Quantity of substance
If a single wavelength is used for downlink transmission, then wavelength resources are reduced and costs are lowered, but the system must handle multiple paths through time division multiplexing
Solution Approach 1:
The patent merges multiple downlink data frames from different paths into a single high-speed downlink bit stream using time division multiplexing, then transmits them over a single wavelength. This reduces wavelength resource requirements while maintaining the ability to serve multiple users
3Ease of manufacture
If TDM-PON is used for FITH service scenario, then deployment costs are low and operation is simple, but latency and jitter are large for new service scenarios
Solution Approach 1:
The patent dynamically adapts the multiplexing scheme based on service requirements. For new service scenarios requiring low latency, it employs wavelength division multiplexing in the uplink direction, while maintaining time division multiplexing for downlink, thus optimizing performance for different service types without requiring complete system replacement
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
The solution effectively reduces latency and jitter, enhances system reliability, and allows operators to quickly expand and deploy new services, such as high-reliability and low-latency services, using existing FITH ODNs.
Implementation Method 1
The first optical modulator is configured to convert the high-speed downlink bit stream into a physical electrical signal, and then modulate the physical electrical signal into a downlink optical signal whose wavelength is Xo
Implementation Method 2
Each optical receiver in the N2 uplink optical receivers separately receives uplink optical signals of different wavelengths
Data Source
AI summary
Embodiments of this application provide an OLT, an ONU, and a system. In a downlink direction, the first OLT is configured to convert received downlink data packets of M1 paths into one downlink optical signal whose wavelength is λo, and the first ONU is configured to receive the downlink optical signal, and output a target user data packet after processing the downlink optical signal. In an uplink direction, the first ONU is configured to convert received uplink data packets into an uplink optical signal whose wavelength is λi, and the first OLT is configured to receive a plurality of uplink optical signals of different wavelengths, and output user data packets of a corresponding quantity of paths after processing.