Headend Scheduler for Two-Tier Network Scheduling
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Solution Overview
Problem
Two-tier networks with different media, such as optical and coaxial, face challenges in scheduling upstream transmission due to protocol differences, leading to increased latency and buffering delays.
Innovation Solution
A headend node with a scheduler and message translator is used to allocate bandwidth and schedule upstream transmission times, generating MAP and GATE messages to coordinate data transmission across the network, ensuring efficient data flow and minimizing delays by aligning transmission times with data arrival at branch nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional scheduling methods are used in two-tier networks with different media, then protocol compatibility is maintained, but scheduling delays and buffering delays increase
Solution Approach 1:
The patent introduces a centralized scheduler at the headend node that acts as an intermediary to coordinate transmissions between end stations and branch nodes. This scheduler generates MAP messages for downstream transmissions and GATE messages for upstream transmissions, translating between different media protocols (optical PON and coaxial DOCSIS) and aligning transmission times to minimize buffering delays at branch nodes.
Solution Approach 2:
The scheduler performs preliminary scheduling actions by pre-calculating and allocating transmission time slots before actual data transmissions occur. It determines optimal transmission times for both downstream (MAP messages) and upstream (GATE messages) based on predicted traffic patterns and QoS requirements, allowing branch nodes to prepare buffers in advance and reducing waiting delays.
2Reliability
If bandwidth is allocated without considering QoS, then network simplicity is maintained, but service quality and performance vary
Solution Approach 1:
The scheduler implements local quality differentiation by applying different scheduling algorithms and priority treatments to different service flows based on their QoS requirements. It maintains separate service flow identifiers and applies weighted round-robin or priority-based scheduling to ensure real-time traffic receives guaranteed bandwidth while best-effort traffic utilizes remaining capacity, thereby providing differentiated service quality across the network.
3Loss of time
If transmission scheduling does not align with data arrival times, then scheduling is simpler, but buffering delays increase
Solution Approach 1:
The scheduler employs feedback mechanisms by monitoring actual transmission completion times and buffer status reports from branch nodes. It uses this feedback to dynamically adjust future scheduling decisions, refining its estimates of data arrival times and optimizing the alignment between scheduled transmission slots and actual data availability, thereby minimizing buffering delays through iterative improvement.
Data Source
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AI summary
A method, system and computer program product to schedule transmissions in a two-tier network are provided. In an example, the system includes a Data Over Cable Service Interface Specification (DOCSIS) scheduler configured to generate a MAP message to allocate bandwidth and a first instance in time to a cable modem to transmit data to a branch node. The system further includes a MAP message translator coupled to the DOCSIS scheduler and configured to determine a second instance in time at which data from the cable modem arrives at the branch node and generate a GATE message that grants the branch node bandwidth to transmit the data received from the cable modem at the second instance in time to a headend node.