Presentation Time Offset Alignment for Symmetric RoE Delays
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Solution Overview
Problem
The manual configuration of presentation time offsets in communication systems is tedious and complicated, and there is a lack of a feasible technical solution for aligning presentation time offsets in different communication directions, particularly in Radio over Ethernet (RoE) applications, to ensure symmetric delays in uplink and downlink paths as required by standards like CPRI.
Innovation Solution
A method and apparatus for communication devices to automatically align presentation time offsets by determining and adjusting them based on the longer initial duration received from a peer device, allowing each device to set its own offset equal to the peer's offset, thereby enhancing automation in setting these offsets without operator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual configuration of presentation time offsets is used, then the system can control end-to-end delay, but the operation becomes tedious and complicated
Solution Approach 1:
The communication device automatically determines and adjusts its own presentation time offset without requiring manual operator intervention. The device measures the actual transmission delay, compares it with the target delay, and self-adjusts the offset to achieve the desired end-to-end delay control, thereby eliminating the tedious manual configuration process while maintaining reliable delay control.
Solution Approach 2:
The system implements a feedback mechanism where the device continuously monitors the actual transmission delay, compares it with the target delay value, and adjusts the presentation time offset accordingly. This closed-loop feedback enables automatic optimization of the offset to achieve the desired end-to-end delay while adapting to changing network conditions.
2Ease of operation
If automatic adjustment of presentation time offsets is implemented, then operational complexity is reduced, but device complexity increases
Solution Approach 1:
The device performs preliminary actions by pre-configuring the presentation time offset based on estimated transmission delay and target delay values before actual data transmission begins. This preliminary setup reduces the complexity of continuous adjustments during operation, as the initial offset is already optimized to achieve the desired end-to-end delay.
Solution Approach 2:
The system dynamically changes the presentation time offset parameter based on measured transmission delay and target delay comparisons. By adjusting this single critical parameter, the device achieves automatic optimization of end-to-end delay without requiring complex multi-parameter configuration mechanisms, thus balancing automation with implementation complexity.
3Stability of the object's composition
If presentation time offsets are aligned in both communication directions, then symmetric delays are achieved, but the alignment process becomes complex
Solution Approach 1:
The patent addresses delay symmetry by recognizing that uplink and downlink paths may have different transmission characteristics. The device independently determines presentation time offsets for each communication direction based on their respective measured delays and target delays. This asymmetric approach allows each direction to be optimized independently, achieving overall delay symmetry without forcing artificial constraints that would increase alignment complexity.
Solution Approach 2:
The alignment process is segmented into independent operations for each communication direction. The device separately measures and adjusts the presentation time offset for uplink transmission and downlink transmission, rather than attempting a single complex synchronized alignment. This segmentation simplifies the overall alignment process while achieving symmetric delay characteristics in both directions.
Data Source
AI summary
In the method, the first device may transmit to a second device a first initial duration of the first presentation time offset, where the first presentation time offset is a period from data being input to the first device to the data being output from the second device. Besides, the first device may receive, from the second device, the second initial duration of a second presentation time offset, where the second presentation time offset is a period from data being input to the second device to the data being output from the first device. Afterwards, the first device may determine an adjusted duration of the first presentation time offset based on a longer one of the first initial duration and the second initial duration.