SFP+ Transceiver Architecture for PON Density and Cost Reduction
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Solution Overview
Problem
Current passive optical network (PON) systems face inefficiencies due to the need for custom-designed optical line terminal (OLT) line cards that are expensive and wasteful of capacity, especially when the number of subscribers is low, and require different line cards for 1G and 10G EPONs, limiting density and performance.
Innovation Solution
The use of enhanced small form-factor pluggable (SFP+) transceiver modules for 1G and 10G EPONs, allowing for independent operation and integration of MAC and PHY layers, enabling efficient coexistence and reducing the need for large XFP transceivers, which improves density and performance by supporting both data rates with compact SFP+ modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If custom-designed OLT line cards are used to aggregate traffic from multiple downstream PONs, then traffic aggregation capability is improved, but capital expenditure and device complexity increase
Solution Approach 1:
The patent segments the OLT functionality by separating the MAC layer (in the OLT line card) from the PHY layer (in the optical module). This allows the optical module to be independently designed and replaced without changing the OLT line card, reducing overall system complexity while maintaining traffic aggregation capability.
Solution Approach 2:
The patent creates a universal optical module interface that can support multiple PON types (1G EPON, 10G EPON, 10G XG-PON) through a single standardized connection. This multi-functional optical module reduces the need for multiple specialized line cards, thereby reducing device complexity while maintaining versatility.
2Ease of manufacture
If custom-designed OLT line cards with fixed number of OLT chips are deployed, then initial network deployment is simplified, but capacity waste occurs when number of subscribers is low
Solution Approach 1:
The patent enables dynamic configuration of the OLT line card by allowing the number and type of optical modules to be changed based on the actual number of subscribers. This dynamic adaptability prevents capacity waste while maintaining ease of initial deployment through standardized interfaces.
Solution Approach 2:
The patent allows changing the parameters of the optical module interface (data rate, protocol type) to match the actual deployment needs. This parameter flexibility enables the system to adapt from 1G to 10G speeds and between different PON types without replacing the entire line card, reducing capacity waste while maintaining deployment simplicity.
3Reliability
If separate line cards are used for 1G and 10G EPONs, then data rate specificity is improved, but network density and space utilization deteriorate
Solution Approach 1:
The patent designs a universal optical module interface that can operate at both 1G and 10G data rates and support multiple PON types. This multi-functional interface eliminates the need for separate line cards for different data rates, thereby increasing network density while maintaining reliable data rate support through proper protocol configuration.
4Reliability
If XFP transceivers are used for 10G EPON, then optical performance is improved, but device size and density deteriorate
Solution Approach 1:
The patent changes the physical interface parameters by using SFP+ transceivers instead of XFP transceivers, achieving a compact form factor while maintaining 10G EPON optical performance through optimized optical components and signal processing in the modular design.
Data Source
AI summary
One embodiment provides an optical line terminal (OLT) module in a network device. The OLT module includes an optical signal module, an OLT management module, a scheduler module, and a forwarding module. The optical signal module transmits optical signals to and receives optical signals from a number of optical network units (ONUs). During operation, the OLT management module identifies a remote OLT module operating at a lower upstream data rate than the OLT module. The scheduler module identifies a report message received from a first ONU operating at the lower upstream data rate and generates a grant corresponding to the report message. A grant specifies a time slot for an upstream data burst. The scheduler module includes the grant in a notification frame destined for the remote OLT module. The forwarding module forwards the notification frame to an internal switch of the network device.