Dynamic Bandwidth Allocation Preventing Buffer Overflow in PON Systems
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Solution Overview
Problem
In conventional PON systems, buffer overflow can occur during upstream frame relay, leading to frame discarding and impaired QoS, especially for high-priority frames like VoIP or video, due to increased data from VLAN tagging, MAC encapsulation, or mismatched sending and reception rates, which existing solutions attempt to address by increasing buffer capacity at a higher cost.
Innovation Solution
A dynamic bandwidth allocation apparatus that calculates an allocated bandwidth upper limit based on reception and sending rates, and changes in data amounts, allowing for secure relay of upstream frames without increasing buffer capacity, by managing and dynamically allocating bandwidth to prevent buffer overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If buffer capacity is increased to prevent buffer overflow during upstream frame relay, then frame discarding is prevented and QoS is maintained, but device complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by calculating the allocated bandwidth upper limit in advance based on reception rate, sending rate, and data amount changes before actual frame relay occurs. This pre-calculation prevents buffer overflow from happening in the first place, eliminating the need to increase buffer capacity while maintaining frame relay reliability.
Solution Approach 2:
The patent changes the parameter of bandwidth allocation by introducing an allocated bandwidth upper limit that is dynamically calculated based on reception rate, sending rate, and data amount changes. This parameter change allows the system to prevent buffer overflow through intelligent bandwidth management rather than increasing physical buffer capacity.
2Adaptability or versatility
If centralized-type DBA with smaller grant cycle for low delay class is used, then compatibility between effective uses of low delay and bandwidth is achieved, but bandwidth allocation precision for specific service classes deteriorates
Solution Approach 1:
The patent applies local quality by calculating the allocated bandwidth upper limit specifically for each service class based on its unique reception rate, sending rate, and data amount characteristics. This allows different service classes to receive customized bandwidth allocation precision while maintaining the overall grant cycle structure, thus preserving both compatibility and precision.
Data Source
AI summary
A dynamic bandwidth allocation apparatus 12 of the present invention is mounted on, for example, an optical line terminal 1 in a PON system that relays upstream frames F1 and F2 received from optical network units 2, to upper networks 6. The dynamic bandwidth allocation apparatus 12 calculates, based on the reception rates of the upstream frames F1 and F2 from the optical network units 2, the sending rates of relay destinations of the upstream frames F1 and F2, and changes in the amounts of data occurring upon relaying the upstream frames F1 and F2, allocated bandwidth upper limits (max_bw) at which even when the amounts of data increase, the upstream frames F1 and F2 can be relayed; and dynamically allocates amounts of upstream transmission for the respective optical network units 2 in the range of the calculated allocated bandwidth upper limits (max_bw).