CPRI Signal Multiplexing with Sync Pattern Frame Head Recovery
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Solution Overview
Problem
Current methods for multiplexing CPRI signals in OTU frames using 8B10B coding result in increased bandwidth and transmission delay due to the need for frame head alignment, which is not feasible for low-delay applications in mobile fronthaul systems.
Innovation Solution
A transmission device that decodes and scrambles each information sequence, adding a synchronous pattern to indicate the frame head, allowing for immediate multiplexing without the need for frame head alignment, thereby reducing bandwidth and delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frame head alignment is performed to identify CPRI frame heads after decoding, then frame head identification is enabled, but transmission delay increases to 66.67 microseconds
Solution Approach 1:
The invention applies preliminary action by inserting a known synchronous pattern at the frame head position before multiplexing. This allows the receiving end to identify frame heads immediately without waiting for the 66.67 microsecond hyperframe period, thereby reducing transmission delay while maintaining accurate frame head identification.
2Quantity of substance
If 8B10B code is decoded to compress bandwidth, then containing efficiency improves, but head information of CPRI signal is lost
Solution Approach 1:
The invention uses an intermediary synchronous pattern that is inserted after decoding. This pattern serves as a mediator that replaces the lost K28.5 code information, allowing frame head identification to be restored without requiring the original 8B10B coded frame structure, thus maintaining bandwidth efficiency while recovering frame head information.
3Loss of time
If multiple CPRI signals are multiplexed without decoding, then transmission delay is reduced, but bandwidth requirement increases to 9.8304 Gbit/s
Solution Approach 1:
The invention applies preliminary action by inserting the synchronous pattern after decoding but before multiplexing. This enables the system to multiplex decoded signals (reducing bandwidth to 7.8643 Gbit/s) while still providing immediate frame head identification capability, thus achieving both bandwidth efficiency and low transmission delay.
4Quantity of substance
If K28.5 code is decoded to eight bits, then bandwidth is reduced, but synchronous pattern cannot be distinguished from other data
Solution Approach 1:
The invention introduces a synchronous pattern as an intermediary element that is explicitly inserted at the frame head position after decoding. This pattern is distinct from other data and can be easily detected, solving the problem of distinguishing the synchronous pattern from regular data while maintaining the bandwidth benefits of decoded transmission.
Data Source
AI summary
A transmission device of a signal transmission system multiplexing and transmitting a plurality of 8B10B-coded information sequences, which includes: conversion units the number of which is identical to the number of the information sequences, to perform 8B10B-decoding of each of the information sequences, receive one of the information sequences after the decoding, scramble the received information sequence, and add a synchronous pattern indicating a head of a frame to the scrambled information sequence; and a multiplexing unit to multiplex the information sequence outputted from each of the conversion units.