Relative Phase Measurement and Alignment of 66B Encoded Signals
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Solution Overview
Problem
Existing systems fail to maintain the relative phase relationship of 66B encoded signals, such as Ethernet and Fibre Channel, when mapped into protocols like OTN, due to phase variations introduced by OTN's elastic stores, which are difficult to control, especially across multiple stages and varying paths.
Innovation Solution
A method and apparatus for relative phase measurement and alignment of 66B encoded signals at the client layer, using periodically converted sync headers to determine and align phases, with circuitry to program delay elements based on phase differences, ensuring consistent latency and propagation delay across transport networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If OTN elastic stores are used to transport multiple 10 Gigabit Ethernet signals, then the transport network can carry multiple signals, but the relative phase relationship between signals is not maintained due to delay skew
Solution Approach 1:
The system uses feedback from phase measurement to actively compensate for phase variations. The phase measurement unit continuously monitors the relative phase between signals, and the compensation mechanism adjusts timing based on this feedback to maintain phase relationships despite elastic store delays
Solution Approach 2:
The system changes the timing parameters of signal transmission to compensate for phase variations. By dynamically adjusting transmission timing based on measured phase differences, the system maintains consistent relative phase relationships even when signals traverse different paths through the OTN network
2Reliability
If the depth of elastic stores is tightly controlled, then phase variations are reduced, but the complexity of controlling elastic stores increases
Solution Approach 1:
The system extracts phase information from the data stream using sync headers, separating the phase measurement function from the elastic store control function. This allows independent optimization of each function without increasing overall system complexity
Solution Approach 2:
The system introduces an intermediary phase measurement and compensation mechanism between the elastic stores and the data output. This intermediary layer handles the complexity of phase control independently, shielding the elastic store depth control from complex phase synchronization requirements
3Productivity
If multiple stages of OTN mapping are used, then more signals can be transported, but multiple inline elastic stores need to be controlled which increases complexity
Solution Approach 1:
The phase measurement and compensation mechanism is designed to work universally across multiple OTN mapping stages and elastic store locations. A single implementation can manage phase relationships throughout the entire signal path, eliminating the need for separate control mechanisms at each stage
4Adaptability or versatility
If 66B encoded signals are mapped into OTN, then the signals can be transported over the transport network, but phase variations are introduced that affect latency
Solution Approach 1:
The system performs preliminary phase measurement and compensation at the ingress point of the OTN network, before signals enter the transport network. By pre-aligning phases and measuring timing characteristics upfront, the system can compensate for latency variations that will occur during transport
Data Source
AI summary
Systems and methods for the relative phase measurement and alignment of 66B encoded signals include receiving a plurality of 66B encoded signals each comprising sync headers which are periodically converted, determining a phase of each of the plurality of 66B encoded signals based on the periodically converted sync headers, and aligning the phase of each of the plurality of 66B encoded signals based on the determining. The periodically converted sync headers can include changing one of a first bit and a second bit of the sync header. A period of the periodically converted sync header can be set at twice a phase difference which is compensated at an egress point of the plurality of 66B encoded signals.