Optical Access Network Collision Prevention via Auxiliary Waves
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Solution Overview
Problem
Optical link transmission networks in small geographical areas face challenges with signal collisions and sub-optimal resource utilization due to the difficulty in synchronizing stations for time division multiple access (TDMA) and the poor performance of carrier sense multiple access/collision detection (CSMA/CD) in tree-configured networks.
Innovation Solution
An optical transmission network with a concentrator and stations connected via an optical interconnection tree, utilizing an emulator to send auxiliary waves and control the sending periods of stations to prevent collisions, allowing decentralized and cost-effective management of station access without the need for extensive synchronization or control links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time division multiple access (TDMA) is used to prevent signal collisions, then collision prevention is improved, but synchronization complexity and system cost increase
Solution Approach 1:
The patent introduces an intermediary mechanism (the emulator sending auxiliary waves) that mediates between stations and the concentrator to control access rights. This mediator eliminates the need for complex direct synchronization between stations by using optical waves as a controlling intermediary signal.
Solution Approach 2:
The patent replaces complex electrical synchronization mechanisms with optical wave-based control. Instead of using electrical signals for timing synchronization, the system uses optical auxiliary waves to convey access control information, substituting a simpler optical mechanism for complex electrical synchronization.
2Device complexity
If carrier sense multiple access/collision detection (CSMA/CD) is used for decentralized access control, then system cost is reduced, but network performance and bandwidth utilization deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the concentrator sends auxiliary waves back through the access links to stations. This feedback signal carries information about network status and access rights, enabling stations to adjust their transmission behavior based on real-time network conditions, thereby improving bandwidth utilization.
Solution Approach 2:
The patent introduces dynamic control of access rights through time-varying auxiliary waves. The access control parameters are not fixed but dynamically adjusted based on network traffic conditions, allowing the system to adapt to changing bandwidth requirements and optimize overall network performance.
3Productivity
If centralized management with controllers is implemented to optimize resource allocation, then bandwidth utilization is improved, but system complexity and cost increase
Solution Approach 1:
The patent makes the concentrator serve multiple functions: it acts as both the signal distribution hub and the control center for resource allocation. By combining these functions in a single device, the system achieves centralized management capabilities without requiring separate controller devices, thereby reducing overall system complexity.
4Adaptability or versatility
If separate control links are added to enable decentralized dialogue between stations and controllers, then adaptability is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the existing access links serve dual purposes: both data transmission and control signal carrying. The same optical links that carry user data also carry the auxiliary control waves, eliminating the need for separate dedicated control links and reducing system complexity.
Data Source
AI summary
The network comprises an optical interconnection tree linking sending points of stations to a receiving point of a concentrator via access links (F1-F3), a coupling system (C) and a common optical link (OL). The stations can send optical signals (λu1, λu2, λu3) each carried by the same “uplink” wavelength (λu). Each station includes a carrier detection system able to detect the presence at its sending point (Ki) of an optical wave at said uplink wavelength (λu) that was not sent by the same station. The detection system cooperates with sending control means to inactivate sending if such presence is detected. The network further includes: an emulator (LDa, Ca, G1-G3) adapted to send auxiliary waves (λa1, λa2, λa3) at said uplink wavelength (λu) and to couple them into the access links (F1-F3) so that they propagate in the downlink propagation direction; and a control system (2a) of the emulator for selectively activating the sending of the auxiliary waves. The invention is particularly applicable to optical access or metropolitan networks.