Rate-Adaptive OTN Frame Slot Allocation
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Solution Overview
Problem
Current Optical Transport Networks (OTNs) are limited in efficiently utilizing channel capacity due to fixed data rates, which do not adapt to varying link conditions such as fiber length and quality, leading to underutilization of available capacity.
Innovation Solution
The method involves adapting data rates by varying the number of slots allocated to client data in OTN frames, with unused slots filled either with forward error correction (FEC) parity bits or dummy bits, allowing for automatic detection and decoding of variable-rate frames without additional signaling, while maintaining existing serial interfaces and signaling schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed data rates are used in OTN, then standard compliance and interface simplicity are maintained, but channel capacity utilization is inefficient
Solution Approach 1:
The patent applies dynamics by making the OTN frame structure adaptable through variable slot allocation. The number of slots allocated to client data varies dynamically based on channel conditions, while the overall frame structure remains consistent with G.709 standards. This allows the system to transition from static fixed-rate operation to dynamic rate adaptation without fundamental structural changes.
Solution Approach 2:
The patent changes the parameter of slot allocation to achieve rate adaptation. By varying the number of slots assigned to client data within the OTN frame structure, the system can adjust data rates to match channel capacity while maintaining standard compliance. This parameter change approach allows flexible rate adaptation without requiring new frame formats.
2Productivity
If variable data rates are implemented, then spectral efficiency is enhanced, but compatibility with existing interfaces may be compromised
Solution Approach 1:
The patent achieves universality by designing a variable slot allocation mechanism that works within the existing G.709 OTN frame structure. The same frame format accommodates both fixed and variable data rates, allowing the system to maintain compatibility with existing interfaces while enabling rate adaptation for improved spectral efficiency on suitable links.
Solution Approach 2:
The patent applies partial action by implementing rate adaptation selectively rather than universally. The variable slot allocation is used to enhance spectral efficiency where channel conditions permit, while maintaining standard fixed-rate operation where compatibility is paramount. This partial implementation allows the system to gain performance benefits without compromising overall interface compatibility.
3Quantity of substance
If slots are allocated to client data, then data transmission capacity is maximized, but unused slots require filling mechanisms increasing complexity
Solution Approach 1:
The patent applies discarding and recovering by allowing unused slots to be filled with dummy bits that are subsequently discarded at the receiving end. This approach simplifies the transmission process by not requiring complex recovery mechanisms, as the dummy bits in unallocated slots are simply removed during reception, enabling flexible slot allocation without proportionally increasing system complexity.
Data Source
AI summary
In an Optical Transport Network (OTN) system, methods and devices are provided for communicating rate-adaptive OTUk frames. One method determines channel statistics for a fiber span connecting a transmitter to a receiver. A client input data rate is determined that is sufficient to meet a minimum communication threshold, and a rate-adaptive OTUk frame format is determined sufficient to carry the client input data rate. The format comprises a set of (n) allocated slots of client input data in a rate-adaptive OTUk frame comprising (m) slots, where (n) is less than or equal to (m). The method then fills the rate-adaptive OTUk frame, including (m−n) unallocated slots, using one of two processes. The first process fills the rate-adaptive OTUk frame with parity bits computed from client input data. The second process fills at least a portion of the rate-adaptive OTUk frame with and dummy bits.