Dynamic Bandwidth Allocation in Passive Optical Networks
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Solution Overview
Problem
Existing methods for dynamically allocating upstream bandwidth in passive optical networks, such as GPONs, do not optimize bandwidth usage, leading to partial utilization of available bandwidth during frame periods when not all traffic flows have expired timers, resulting in unused bandwidth.
Innovation Solution
A method where the Optical Line Termination (OLT) allocates upstream bandwidth to traffic flows with not yet expired timers if bandwidth is available, prioritizing those with more bytes waiting to be transmitted, and using a timer-based system to manage and allocate fixed, assured, non-assured, and best effort bandwidths dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the OLT waits for timers to expire before allocating upstream bandwidth, then timer-based bandwidth allocation is simple to implement, but bandwidth utilization is inefficient and unused bandwidth remains
Solution Approach 1:
The patent implements dynamic bandwidth allocation where the OLT can allocate upstream bandwidth both when timers expire (maintaining timer-based control) and when bandwidth is available (improving utilization). This dynamic approach allows the system to adapt between timer-driven allocation and availability-driven allocation, resolving the contradiction between simplicity and efficiency.
Solution Approach 2:
The OLT performs preliminary checks to determine if bandwidth is available before waiting for timer expiration. When bandwidth is available, the OLT proactively allocates it to traffic flows without waiting for timer expiration, thus preventing bandwidth idle time and improving overall utilization while maintaining the timer-based framework.
2Productivity
If the OLT allocates bandwidth only to traffic flows with expired timers, then allocation rules are simple, but traffic flows with pending data experience delays and bandwidth remains unused
Solution Approach 1:
The patent ensures continuous utilization of upstream bandwidth by allowing the OLT to allocate bandwidth not only when timers expire but also when bandwidth is available and traffic flows have data to transmit. This eliminates idle bandwidth periods and maintains continuous useful action, resolving the contradiction between simple allocation rules and efficient bandwidth usage.
3Productivity
If the OLT serves multiple traffic flows simultaneously, then bandwidth is fully utilized, but collision avoidance becomes more complex
Solution Approach 1:
The patent segments upstream bandwidth allocation into multiple time slots or grants, each assigned to specific traffic flows. By dividing the bandwidth allocation process into discrete segments rather than simultaneous allocation, the system achieves full bandwidth utilization while maintaining manageable collision avoidance through structured time-division multiplexing.
Data Source
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AI summary
It is disclosed a method of allocating upstream bandwidth to at least a first upstream traffic flow and a second upstream traffic flow in a passive optical access network. The method comprises: a) associating a first timer to the first upstream traffic flow; b) associating a second timer to the second upstream traffic flow. The method comprises, during a given frame period: - if said first timer is at its expiration value and said second timer is not at its expiration value: c) allocating a first portion of said upstream bandwidth to said first upstream traffic flow, d) verifying if a second portion of said upstream bandwidth is left after performing said step c); and e) in the affirmative, allocating at least part of said second portion of said upstream bandwidth to said second upstream traffic flow before said second timer is at its expiration value, - if said first timer and said second timer are not at their expiration value, f) allocating at least part of said upstream bandwidth to at least one of said first and second upstream traffic flows before respective timers are at their expiration values.