Fronthaul Synchronization Packet Timing Against IQ Contention
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Solution Overview
Problem
In 5G radio access networks, synchronization packets experience contention delays with in-phase and quadrature packets over the fronthaul network due to non-integer slot intervals, impairing synchronization performance.
Innovation Solution
A timing master is implemented to transmit synchronization packets at unique and distributed transmission offsets relative to the slot period, avoiding contention by ensuring each packet's transmission time offset is distinct and spread throughout the slot duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization packets are transmitted at a predetermined rate over the fronthaul network, then synchronization is established between DU and RU, but contention delay occurs with IQ data packets due to non-integer slot intervals
Solution Approach 1:
The patent applies dynamics by making the transmission time offset of synchronization packets adjustable and adaptable. Instead of using a fixed transmission schedule that causes periodic contention, the system dynamically selects transmission offsets that avoid collision with IQ data packets. This is achieved by calculating offsets based on the relationship between synchronization packet rate and slot rate, and adjusting the transmission timing to fall within appropriate slots rather than at fixed intervals, thereby eliminating contention delay while maintaining synchronization reliability.
2Ease of operation
If Synch packet transmission rate is set to a power of 2 as recommended by O-RAN, then transmission simplicity is maintained, but the number of slots between packets becomes non-integer causing alignment issues with slot-based IQ transmissions
Solution Approach 1:
The patent applies parameter changes by modifying the transmission time offset parameter of synchronization packets. When the calculated number of slots between packets is non-integer, the system adjusts the transmission offset within the slot structure to achieve proper alignment. This allows the system to maintain the simple power-of-2 transmission rate recommendation while compensating for the misalignment issue by dynamically adjusting the timing offset parameter, ensuring packets are transmitted at appropriate positions within slots rather than at fixed intervals.
Data Source
AI summary
Techniques are described for avoiding contention between synchronization packets (for example, Institute of Electrical and Electronics Engineers (IEEE) 1588 Precision Time Protocol (PTP) synchronization packets) and in-phase and quadrature (IQ) packets communicated over a fronthaul network used in a radio access network (for example, a Fifth Generation (5G) radio access network).