Optical Network Scheduler Preventing Beat Interference
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Solution Overview
Problem
Conventional RFoG networks face optical beat interference issues when multiple upstream transmitters send signals at the same or nearly identical wavelengths, leading to damaged upstream optical signals and hindered communication deciphering.
Innovation Solution
Implementing a multi-port optical resource that analyzes upstream communications to detect client devices' passive optical networks, assigns class information based on network addresses or transit times, and schedules transmissions to prevent simultaneous transmissions from devices in the same network, thereby avoiding optical beat interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple upstream transmitters transmit at the same or nearly identical wavelengths simultaneously, then upstream communication capacity increases, but optical beat interference occurs causing signal damage
Solution Approach 1:
The patent segments the upstream transmission system by assigning different time slots to different ONUs. The scheduler divides the upstream transmission opportunity into discrete time slots, allowing only one ONU to transmit at a time. This temporal segmentation eliminates optical beat interference while maintaining communication capacity through sequential transmissions.
Solution Approach 2:
The patent implements periodic action through cyclically shifting time slots assigned to different ONUs. The scheduler uses a round-robin approach where each ONU is assigned a time slot that rotates through a predefined sequence. This periodic allocation ensures fair access and prevents simultaneous transmissions, eliminating optical beat interference while maintaining system productivity.
2Productivity
If ONUs transmit simultaneously in upstream direction, then transmission efficiency increases, but optical receiver receives combined optical power from multiple lasers causing interference
Solution Approach 1:
The patent applies preliminary action by having the scheduler assign time slots before actual transmissions occur. The scheduler receives upstream grant information, determines appropriate time slots for each ONU based on their identifiers, and pre-configures the transmission schedule. This preliminary coordination ensures that when transmissions occur, only one ONU is active at a time, preventing optical beat interference and maintaining signal deciphering accuracy.
3Object-affected harmful factors
If wavelength spacing between lasers is increased to avoid interference, then optical beat interference decreases, but transmission bandwidth utilization decreases
Solution Approach 1:
The patent resolves this contradiction by moving the interference avoidance mechanism from the wavelength dimension to the time dimension. Instead of increasing wavelength spacing to prevent optical beat interference, the system maintains all ONUs operating at the same wavelength and uses temporal separation (time slots) to prevent simultaneous transmissions. This dimensional shift allows full wavelength utilization while eliminating interference through time-division multiplexing.
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 effectively prevents optical beat interference by ensuring only one client device from each passive optical network transmits at a time, improving upstream communication efficiency and accuracy.
Implementation Method 1
An optical detection device in the upstream device converts the optical signal into a respective electrical output that is proportional to the instantaneous sum of the combined optical powers contributed by the two lasers
Data Source
AI summary
A communication resource in a network environment analyzes upstream communications received over multiple passive optical networks. The upstream communications are received from multiple client devices in different passive optical networks. Based on analysis of the upstream communications, via an active or passive approach, a corresponding communication resource detects in which of the multiple passive optical networks each of the client devices reside. A scheduler resource can be configured to use the class information as a basis to schedule subsequent upstream communication, avoiding occurrence of optical beat interference.