Dynamic Bandwidth Assignment in Passive Optical Networks
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Solution Overview
Problem
In passive optical networks, current dynamic bandwidth assignment mechanisms experience delays and data packet losses due to insufficient buffer capacity when handling massive burst data traffic, as they set a fixed maximum bandwidth grant size, leading to delayed and incomplete data transmission.
Innovation Solution
Implementing a dynamic bandwidth assignment method that sets a maximum bandwidth grant size and a maximum burst bandwidth grant size, allowing the optical line terminal to dynamically adjust bandwidth allocation based on request, ensuring timely and accurate transmission of massive uplink burst data traffic by delivering the requested bandwidth grant size when it exceeds the maximum but is within the burst threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the OLT sets a fixed maximum bandwidth grant size for T-CONT, then the bandwidth allocation is simple and stable, but transmission delays and packet losses occur when burst traffic exceeds the fixed limit
Solution Approach 1:
The patent introduces a two-tier bandwidth grant mechanism where the OLT dynamically adjusts the bandwidth grant size based on the type of traffic burst. For grant traffic, the OLT grants bandwidth up to the maximum bandwidth grant size. For non-grant traffic, the OLT grants bandwidth up to a separate maximum non-grant bandwidth grant size. This dynamic adjustment resolves the contradiction by allowing the system to adapt bandwidth allocation to actual traffic needs while maintaining stability through predefined limits.
Solution Approach 2:
The patent changes the bandwidth grant parameter from a single fixed value to two distinct parameters: maximum bandwidth grant size for grant traffic and maximum non-grant bandwidth grant size for non-grant traffic. This parameter change allows the system to optimize bandwidth utilization for different traffic types simultaneously, preventing both transmission delays and packet losses by ensuring adequate bandwidth allocation for burst traffic while maintaining overall system stability.
2Reliability
If the OLT assigns bandwidth in advance within a grant bandwidth period, then the bandwidth allocation is predictable and stable, but massive burst data packet losses occur when the ONU buffer is insufficient
Solution Approach 1:
The patent segments the bandwidth grant into two distinct categories: grant traffic bandwidth and non-grant traffic bandwidth, each with its own maximum grant size. This segmentation allows the system to reliably allocate bandwidth for scheduled traffic while also providing dedicated bandwidth for unscheduled burst traffic, preventing packet losses due to buffer overflow while maintaining predictable allocation for time-sensitive applications.
Solution Approach 2:
The patent introduces a new intermediary parameter: maximum non-grant bandwidth grant size. This intermediary acts as a buffer between the fixed maximum bandwidth grant size and the actual burst traffic demands. By allocating this intermediate bandwidth capacity specifically for non-grant traffic, the system prevents packet losses when burst traffic exceeds the original fixed limit, while the overall bandwidth utilization increases to accommodate legitimate burst demands.
3Device complexity
If the ONU temporarily buffers non-grant traffic for subsequent transmission, then bandwidth allocation remains stable, but transmission delays increase and service performance deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-allocating maximum non-grant bandwidth grant size before burst traffic arrives. Instead of waiting for traffic to accumulate and then buffering it (which causes delays), the system proactively reserves bandwidth capacity for non-grant traffic in advance. This allows the ONU to transmit burst traffic immediately when it arrives, eliminating transmission delays while keeping bandwidth management simple through predefined limits.
Data Source
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AI summary
The present invention discloses a bandwidth assignment method and apparatus, and an optical network system. The method includes: setting a maximum bandwidth grant size and a maximum burst bandwidth grant size for an optical network unit; receiving a bandwidth assignment request of the optical network unit; and when an optical line terminal determines, according to the bandwidth assignment request, that a bandwidth grant size requested to be assigned in the bandwidth request is greater than the set maximum bandwidth grant size and less than or equal to the set maximum burst bandwidth grant size, determining, by the optical line terminal, in response to the request, to assign the requested bandwidth grant size to the optical network unit. Therefore, timely and accurate transmission of massive uplink burst data traffic is ensured, a transmission delay is reduced, service performance is improved, and system bandwidth utilization is greatly increased.