Bus-Based Optical Network System Reducing Fiber Count
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Solution Overview
Problem
Current FTTH access networks face high installation and maintenance costs due to the large number of optical fibers required, and inefficient bandwidth utilization, leading to increased waiting times for ONUs during heavy loads, which degrades network performance.
Innovation Solution
A bus-based optical network system utilizing TDMA on both upstream and downstream channels with distributed medium access control, allowing each ONU to control slot access based on traffic demands, reducing the need for centralized control and optimizing bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ring topology is used to reduce optical fiber cost, then construction cost is reduced, but the distance between CO and farthest ONU is shorter leading to increased number of COs
Solution Approach 1:
The patent transitions from traditional two-dimensional fiber distribution (ring/star/tree topologies) to a one-dimensional bus topology where optical fibers are arranged linearly. This dimensional change allows ONUs to be distributed along the bus while sharing the same fiber infrastructure, reducing both fiber quantity and CO requirements simultaneously.
Solution Approach 2:
The bus topology creates a universal infrastructure where a single optical fiber bus serves multiple functions: it acts as both the transmission medium and the structural framework for network organization. This multi-functionality eliminates the need for separate CO infrastructure for each service area, reducing overall system complexity.
2Device complexity
If star or tree topology is used to reduce number of COs, then construction cost is reduced, but large amount of optical fibers are required increasing maintenance cost
Solution Approach 1:
The patent merges the functions of multiple COs and their associated fiber networks into a single bus topology. Instead of having separate star or tree networks requiring multiple COs, the bus structure combines all ONUs into a unified infrastructure that shares common optical fibers, reducing both CO count and fiber requirements.
Solution Approach 2:
The bus topology segments the network into logical sections along the linear fiber arrangement, allowing multiple ONUs to be served by a single physical infrastructure. This segmentation enables flexible network organization without requiring additional COs or extensive fiber deployment.
3Productivity
If TDMA is used for medium access control, then bandwidth utilization efficiency is improved, but waiting time for ONUs increases during heavy loads
Solution Approach 1:
The patent implements dynamic bandwidth allocation where the OLT can flexibly adjust slot assignments based on real-time traffic conditions. This dynamic approach allows the system to optimize bandwidth distribution during heavy loads, reducing waiting times while maintaining high utilization efficiency through adaptive slot management.
Solution Approach 2:
The system incorporates feedback mechanisms where the OLT monitors traffic conditions and adjusts TDMA slot allocations accordingly. This feedback loop enables the system to respond to heavy load conditions by reallocating slots to reduce waiting times while maintaining overall bandwidth efficiency through continuous optimization.
Data Source
AI summary
A bus-based optical network system comprising optical fibers, optical line terminals (OLTs), and a plurality of optical network units (ONUs) is revealed. The OLT consists of the near part (OLTN) and the far part (OLTF). Optical fibers respectively form the transmitting and receiver buses (T Bus and R Bus) with the technique of time-division multiple access (TDMA). The slot flows on both buses are in opposite directions. The OLTN performing traffic control is situated in or near a central office (CO) while the OLTF is far from the CO. ONUs, whose MAC performs traffic control, connect with two buses and share their bandwidth. The MAC with traffic control keeps the performance of the network from degradation. The required numbers of COs and optical fibers for establishing the bus-based network are so smaller that the cost of the network can be significantly reduced.