CPRI Node HDLC Packet Arbitration and Extraction
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Solution Overview
Problem
In CPRI daisy chain configurations, only the endpoint REC or RE can manage and write HDLC packets, limiting the ability of intermediate nodes to report status or deliver control messages, which restricts network flexibility and reliability.
Innovation Solution
Implementing a pair of CPRI modules connected through auxiliary interfaces and a local system bus, allowing each node to extract and insert data packets while maintaining HDLC flow, even during soft resets, with an arbitration scheme prioritizing remote packets to prevent data loss or corruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If only endpoint REC or RE manages HDLC packets in CPRI daisy chain, then protocol simplicity is maintained, but network flexibility and reliability deteriorate due to limited status reporting and control message delivery capability
Solution Approach 1:
The patent segments the HDLC packet management function from the endpoint-only model to enable intermediate nodes to also manage packets. Each node in the daisy chain is equipped with packet data buffers and arbitration logic, allowing distributed packet extraction and insertion capabilities while maintaining overall protocol coherence.
Solution Approach 2:
The patent introduces intermediary components at each node including packet data buffers and arbitration logic that mediate between remote and local packets. These intermediaries enable intermediate nodes to successfully manage HDLC packets by buffering and arbitrating between packets from different sources without disrupting the overall HDLC flow.
2Reliability
If intermediate nodes extract and insert HDLC packets, then network reliability improves through better status reporting, but data loss or corruption risk increases without proper arbitration
Solution Approach 1:
The patent implements preliminary action through priority arbitration before packet transmission. The arbitration logic determines the transmission priority of remote packets versus local packets before they are inserted into the HDLC flow, preventing conflicts and potential data corruption that would occur without such pre-processing.
Solution Approach 2:
The patent incorporates feedback mechanisms where nodes report their status and packet handling state back through the HDLC packet management system. This feedback enables the network to monitor and adjust packet flow dynamically, improving reliability while maintaining data integrity through continuous status awareness.
3Reliability
If remote packets are prioritized in arbitration, then data loss prevention is improved, but local packet transmission delay increases
Solution Approach 1:
The patent changes the arbitration parameter from equal treatment to priority-based treatment of packets. By introducing a priority parameter that favors remote packets, the system prevents data loss in the HDLC flow while still providing a defined mechanism for handling local packets, transforming the arbitration behavior from neutral to differentiated.
Data Source
AI summary
A system for use in nodes communicating over a CPRI (common public radio interface) allows each networking node in a daisychain configuration to seamlessly manage the control and management HDLC (high-speed data link control) channel for both uplink and downlink. The connection is kept alive through a soft reset flow. Received HDLC packets can be extracted for use by a local node. Locally generated packets can be inserted into the packet data stream at the datalink layer for onward transmission over the CPRI. The system arbitrates between the locally generated packet data held in a buffer in the local node and remote packet data received from a remote node and held in the local node in a first in first out buffer for onward transmission to a subsequent node after arbitration. Remote packet data is given priority.