CPRI Circuit Buffering for High-Jitter Fronthaul Delivery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In packet-based fronthaul networks, CPRI frame integrity is compromised due to packet delay variations and jitter, leading to packet loss, early/late arrival, and buffer underrun issues, which can cause CPRI link faults and radio connectivity disruptions.
Innovation Solution
Implementing a de-mapper with a buffer and re-timer mechanism that inserts idle data packets to maintain framing integrity, monitors packet arrival and buffer status, and adjusts re-timer output delay to ensure continuous CPRI stream delivery by using sequence numbers or timestamps to identify valid frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If packet-based transport is used to carry CPRI traffic over fronthaul networks, then network flexibility and adaptability are improved, but packet delay variations and jitter cause CPRI frame integrity to deteriorate
Solution Approach 1:
The patent introduces an intermediary buffering mechanism at the de-mapper that mediates between the variable packet-based network transport and the fixed-rate CPRI interface. The buffer absorbs packet delay variations and jitter, providing a stable output stream to the CPRI interface while allowing flexible packet-based transport on the network side.
Solution Approach 2:
The patent implements beforehand cushioning by pre-buffering incoming packets before they are delivered to the CPRI interface. This cushioning mechanism compensates for future packet delay variations and jitter, ensuring that the CPRI interface receives frames at the correct rate regardless of network conditions.
2Area of stationary object
If packets are transmitted over a jitter-prone network, then network coverage and reachability are improved, but packet loss and buffer underrun increase
Solution Approach 1:
The patent applies preliminary action by collecting and buffering packets in advance before they are needed at the CPRI interface. This allows the system to handle packet loss and delays proactively rather than reactively, ensuring continuous CPRI stream delivery even when network conditions cause packet loss.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining a continuous buffered supply of packets that can be delivered to the CPRI interface at the required rate. This continuous buffer supply prevents buffer underrun and ensures uninterrupted CPRI stream delivery despite network jitter and packet loss.
3Reliability
If packets are buffered to compensate for jitter, then CPRI frame integrity is improved, but buffer underrun and packet loss occur during high jitter periods
Solution Approach 1:
The patent implements dynamics by making the buffer size and characteristics adaptable to network conditions. The buffering mechanism dynamically adjusts to handle varying jitter levels, allowing the system to maintain CPRI frame integrity while managing packet availability during high jitter periods through flexible buffer management.
Data Source
AI summary
The present disclosure is directed to ensuring end-to-end packet delivery in a Common Public Radio Interface (CPRI) circuit with a high jitter packet-based fronthaul network. In one aspect, a method includes determining, at a de-mapper, that at least one data packet scheduled to be played out is not available; inserting an idle data packet into a buffer at the de-mapper for each data packet that is not available; continuously monitoring a packet playout process to (1) identify last valid data packet played out, (2) a number of idle data packets inserted, and (3) a number of data packets currently stored in the buffer; and determining that insertion of idle data packets into the buffer should be stopped and a valid data packet to be played out; wherein inserting the idle data packet and the valid data packet ensure link integrity in data packet transmission between two network elements.