RTT-Aware Dynamic Bandwidth Allocation for EPON
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Solution Overview
Problem
Current bandwidth allocation schemes in Ethernet Passive Optical Networks (EPON) and Ethernet Passive Optical Networks over Coaxial (EPoC) systems are inefficient due to the lack of consideration for round trip times (RTTs), leading to idle bandwidth and reduced channel utilization.
Innovation Solution
Implementing a dynamic bandwidth allocation (DBA) scheme that allocates upstream bandwidth based on measured RTTs between the Optical Line Terminal (OLT) and network units, sorting network units by their RTTs to minimize idle time and reduce the number of guard intervals, and grouping allocations for units connected to the same coaxial plant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If dynamic bandwidth allocation is implemented without considering RTT, then bandwidth allocation is simplified, but idle bandwidth increases and channel utilization decreases
Solution Approach 1:
The patent changes the parameter of bandwidth allocation from static to dynamic, and incorporates RTT as a new parameter in the allocation decision process. The OLT measures RTT for each ONU and uses this parameter to adjust time slot allocations, transforming the allocation strategy from uniform to differentiated based on actual network conditions.
Solution Approach 2:
The patent implements a feedback mechanism where the OLT measures the RTT of each ONU continuously and uses this measured information to adjust subsequent bandwidth allocations. The system collects RTT data, processes it through the DBA algorithm, and feeds back optimized time slot allocations to reduce idle bandwidth caused by RTT variations.
2Productivity
If RTT-aware dynamic bandwidth allocation is implemented, then channel utilization improves, but system complexity increases
Solution Approach 1:
The patent performs preliminary RTT measurement and sorting of ONUs before bandwidth allocation. By pre-measuring RTT values and sorting ONUs in ascending order of RTT, the system prepares the necessary information in advance, which simplifies the subsequent allocation process and reduces real-time computational complexity.
Solution Approach 2:
The patent introduces an intermediary sorting step between RTT measurement and bandwidth allocation. ONUs are sorted based on RTT values, creating an ordered sequence that serves as an intermediary structure. This sorting mechanism simplifies the allocation logic by providing a predetermined order for assigning time slots, reducing the complexity of real-time decision-making.
3Loss of time
If network units are sorted by RTT and allocations are grouped, then guard intervals are minimized, but processing complexity increases
Solution Approach 1:
The patent merges allocations for ONUs with similar RTT characteristics and groups them contiguously in the time domain. By combining adjacent time slots for ONUs with comparable RTT values, the system reduces the number of transitions between different RTT groups, thereby minimizing the required guard intervals and reducing idle time.
Data Source
AI summary
An apparatus comprising a receiver configured to receive a plurality of transmission requests from a plurality of end nodes via an optical network and an electrical network, a processor coupled to the receiver and configured to dynamically allocate optical transmission time slots to the end nodes according to measured RTTs of the end nodes, and a transmitter coupled to the processor and configured to transmit the allocated transmission time slots to the end nodes. Also disclosed is a method performed by an OLT comprising receiving a plurality of transmission requests from a plurality of network units via a PON and an electrical network, and allocating optical transmission time slots to the network units dynamically according to measured RTTs of the network units.