Optical Line Terminal Dynamic Bandwidth Allocation
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Solution Overview
Problem
In dynamic bandwidth allocation methods for passive optical networks (PONs), the fixed allocation cycle can result in unnecessary delays when few ONUs request bandwidth, while the floating cycle mode may limit throughput due to minimum allocation cycle constraints.
Innovation Solution
A dynamic bandwidth allocation method that compares the allocation cycle with a predetermined threshold value, allocating remaining bandwidth as best-effort bandwidth if the cycle is below the threshold, allowing for shorter delays without compromising upstream throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed allocation cycle is used in dynamic bandwidth allocation, then bandwidth allocation is simplified and stable, but unnecessary delays occur when few ONUs request bandwidth
Solution Approach 1:
The patent applies dynamics by making the allocation cycle variable rather than fixed. The OLT dynamically adjusts the allocation cycle length based on the number of ONUs requesting bandwidth - using a first allocation cycle when many ONUs request bandwidth and a second, shorter allocation cycle when few ONUs request bandwidth. This resolves the contradiction by allowing the system to switch between fixed-cycle simplicity and variable-cycle efficiency based on actual network conditions.
2Loss of time
If a floating allocation cycle is used to reduce delays, then allocation delay decreases when few ONUs request bandwidth, but upstream throughput is limited by minimum allocation cycle constraints
Solution Approach 1:
The patent uses dynamics to switch between two allocation cycle modes: a first allocation cycle (longer duration) that ensures sufficient upstream throughput when many ONUs are active, and a second allocation cycle (shorter duration) that reduces delays when few ONUs request bandwidth. The OLT selects the appropriate cycle length based on real-time bandwidth request patterns, thus resolving the throughput-delay tradeoff.
Solution Approach 2:
The patent changes the allocation cycle parameter dynamically based on network conditions. By monitoring the number of ONUs requesting bandwidth and adjusting the allocation cycle length accordingly, the system optimizes both throughput and delay performance. This parameter change approach allows the system to adapt to varying traffic conditions without being constrained by fixed or minimum cycle limitations.
3Speed
If the allocation cycle is shortened to reduce delays, then responsiveness improves, but the minimum allocation cycle constraint limits further reduction
Solution Approach 1:
The patent implements dynamics by providing two distinct allocation cycle lengths rather than a single fixed or minimum-constrained cycle. The OLT can select the shorter second allocation cycle to improve responsiveness when few ONUs are active, while switching to the longer first allocation cycle when many ONUs are active to ensure sufficient throughput. This dynamic selection resolves the contradiction between responsiveness and throughput guarantee.
Data Source
AI summary
There is provided an optical line terminal that dynamically allocates communication bandwidth to a plurality of optical network units in an optical communication network, the optical line terminal including a minimum bandwidth allocation unit calculating allocation bandwidth of the plurality of optical network units based on bandwidth request information notified by the plurality of optical network units, a comparison unit comparing an allocation cycle given as the sum total of allocation bandwidth allocated to the plurality of optical network units respectively with a predetermined threshold value, a best-effort bandwidth allocation unit calculating remaining bandwidth as best-effort bandwidth of the plurality of optical network units when the allocation cycle is less than the threshold value, and a bandwidth allocation unit allocating communication bandwidth of the plurality of optical network units based on the allocation bandwidth and the best-effort bandwidth.