Emulating Point-to-Point CPRI Links Over Packet Networks
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Solution Overview
Problem
Current CPRI link infrastructure requires point-to-point connections, which are costly and limit the widespread application of the Common Public Radio Interface (CPRI) protocol, especially in packet networks that are not dedicated or are shared with other traffic.
Innovation Solution
The implementation of a method to emulate a point-to-point link over packet networks using a protocol stack with a multiplexing layer, emulation layer, and pseudo wire layer, allowing CPRI frames to be encapsulated in packets and transmitted over packet switched networks like Ethernet, thereby reducing infrastructure costs and enabling sharing with other traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If point-to-point connections are used for CPRI links, then transmission reliability and timing accuracy are improved, but infrastructure cost and device complexity increase
Solution Approach 1:
The patent introduces a protocol stack with multiple layers (emulation layer, multiplexing layer, packet network layer) as an intermediary between the CPRI protocol and the packet network. This intermediary enables CPRI frames to be transmitted over shared packet networks while maintaining the reliability and timing characteristics of dedicated point-to-point links, thus resolving the contradiction between transmission reliability and infrastructure complexity
Solution Approach 2:
The invention makes the packet network infrastructure universal by enabling it to carry both packet traffic and emulated CPRI traffic simultaneously. The shared packet network infrastructure serves multiple functions: carrying data packets, voice traffic, and synchronized CPRI frames, thereby reducing the need for separate dedicated infrastructure while maintaining reliability
2Reliability
If dedicated point-to-point infrastructure is deployed, then transmission quality and timing synchronization are improved, but cost and ease of deployment worsen
Solution Approach 1:
The patent creates a virtual copy of the point-to-point link characteristics over a shared packet network. The emulation layer replicates the timing and synchronization behavior of dedicated links by using protocol headers (such as MPLS labels with timestamp information) to carry timing data, allowing CPRI frames to be transmitted over cost-effective shared infrastructure while maintaining the timing synchronization properties of dedicated links
Solution Approach 2:
The invention changes the parameters of packet network traffic by introducing specific protocol headers and emulation mechanisms that prioritize and synchronize CPRI frames. By modifying packet parameters (timestamps, priority tags, sequence numbers) in the protocol stack, the system enables cost-effective shared infrastructure to provide the timing synchronization previously only available from expensive dedicated links
Data Source
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AI summary
A CPRI link involves using a protocol stack (230) having a CPRI layer (232) and an emulation layer (234) to emulate a point to point link, to enable the CPRI link to operate over a packet switched network. The emulation layer can be a pseudowire emulation which encapsulates multiple CPRI frames in a packet with overhead. A multiplexing layer such as IP or MPLS can be used, sending the packet over an Ethernet network. The usual need for a point to point infrastructure for the CPRI link can be avoided and the CPRI link can be implemented over more complex but usually cheaper packet networks, thus reducing costs or enabling more widespread application over existing packet networks. This applies whether the packet network is dedicated to the CPRI link, or is shared with other packets. It can be useful for distributed radio base stations.