Optical Line Terminal Grant Scheduler Using Pre-computed Cycles
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Solution Overview
Problem
In optical networks, particularly passive optical networks (PONs), the current scheduling methods for upstream traffic from optical network terminals (ONTs) to optical line terminals (OLTs) are inefficient, leading to inadequate time slot allocation and increased latency due to reactive scheduling and high processing power requirements, especially in systems that do not support status reporting.
Innovation Solution
Implementing a grant scheduler that pre-computes grant cycles pending (GCPs) based on reported or monitored upstream data, allowing for more efficient allocation of time slots and reducing processing power needs by converting data amounts into GCPs before the grant map generation period, thereby improving bandwidth allocation and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the OLT determines upstream grant map after each scheduling round using conventional methods, then the grant map can accommodate different levels of service and past delivery of service, but the processing power and storage capacity requirements become significantly high due to the limited time period available
Solution Approach 1:
The patent applies preliminary action by pre-computing grant cycles pending (GCPs) for each ONT based on their upstream data amounts before the grant map generation period begins. This allows the OLT to have ready-calculated values available when generating the grant map, eliminating the need for complex real-time computations during the scheduling round and significantly reducing processing power requirements while maintaining service quality.
2Loss of information
If the OLT monitors upstream traffic from ONTs that do not support status reporting, then the OLT can determine data amounts, but the OLT fails to proactively schedule time slots and reacts only to data sent, hampering network operation
Solution Approach 1:
The patent implements feedback by continuously monitoring upstream traffic from ONTs and using this information to dynamically adjust and pre-compute grant cycles pending. The monitoring results feed into the GCP calculation, enabling the system to proactively schedule time slots based on actual traffic patterns rather than reacting only after data is sent, thus improving network operation efficiency while handling ONTs without status reporting support.
3Loss of time
If the OLT computes grant map in the limited time period after receiving status reports, then the grant map can be generated for the next scheduling round, but the computation requires significant processing resources
Solution Approach 1:
The patent applies preliminary action by performing the computationally intensive GCP calculations before the grant map generation period. By pre-computing these values based on upstream data amounts and monitoring results, the system reduces the computation burden during the critical 125 microsecond window, allowing the grant map to be generated quickly with minimal processing power while maintaining accurate scheduling.
4Adaptability or versatility
If the OLT uses reactive scheduling for ONTs without status reporting support, then the OLT can handle these ONTs, but adequate time slots are not scheduled and latency increases
Solution Approach 1:
The patent uses feedback from upstream traffic monitoring to dynamically adjust grant cycles pending for ONTs without status reporting support. By continuously monitoring the traffic these ONTs send and using this feedback to pre-compute appropriate GCPs, the system transitions from purely reactive scheduling to a proactive approach that anticipates scheduling needs, reducing latency while maintaining compatibility with diverse ONT types.
Data Source
AI summary
In general, techniques are described for monitoring downstream traffic in order to schedule delivery of upstream traffic in a computer network. The techniques may be implemented by an optical line terminal (OLT) comprising a control unit and an interface. The control unit determines an amount of upstream data that is waiting at one of a plurality of ONTs to be transmitted upstream to the OLT, and determines an amount of downstream data that is transmitted by the OLT to this ONT. The control unit increases the determined amount of upstream data based on the determined amount of downstream data transmitted by the OLT to the ONTs and, after increasing the determined amount of upstream data, generates an upstream grant map that grants time slots to the ONTs based on the determined amount of upstream data. The interface transmits the upstream grant map downstream to the ONTs.