Uplink Summation Bit Width Extension for Distributed Antenna Systems
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Solution Overview
Problem
In distributed antenna systems, digital uplink signal summation often results in bit width overflow due to limited bit width, leading to signal stray and reduced system performance, with existing solutions requiring resource-intensive multiplication and complex processing, especially in systems with multiple channels and large bandwidth.
Innovation Solution
The proposed method involves bit width extension and full precision summation of uplink CPRI data streams, extracting orthogonal IQ signals, determining attenuation values for fast and slow fading, and generating a gain table to shift and truncate the IQ signals, thereby preventing overflow without requiring extensive FPGA resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal power summation with threshold comparison is performed, then signal overflow can be prevented, but multiplication processing modules and FPGA resources are heavily consumed
Solution Approach 1:
The patent changes the processing parameter from power domain (requiring multiplication) to amplitude domain (requiring only addition). By operating on the amplitude values of IQ signals directly and comparing against a threshold, the system prevents overflow without needing complex multiplication modules, significantly reducing FPGA resource consumption while maintaining reliability
Solution Approach 2:
The patent replaces the mechanical multiplication operation with a simpler addition operation in the amplitude domain. Instead of multiplying signals to calculate power, the system adds amplitude values directly, substituting a complex operation with a simpler one that achieves the same overflow prevention goal with fewer resources
2Reliability
If each IQ signal is processed separately with adjustable values, then signal power can be reduced below threshold, but processing becomes cumbersome and consumes excessive logic resources
Solution Approach 1:
The patent merges the processing of multiple IQ signals into a single unified operation. Instead of processing each signal separately with individual adjustable values, the system sums the amplitude values of all IQ signals together and applies a single threshold comparison, dramatically simplifying the processing workflow and reducing logic resource consumption
3Measurement precision
If CPRI data streams are unframed and re-mapped for power calculation, then accurate power measurement can be achieved, but system complexity increases
Solution Approach 1:
The patent extracts only the essential amplitude information from the CPRI data streams needed for overflow prevention, rather than performing complete power measurement which requires unframing and re-mapping. By taking out only the necessary amplitude values and operating directly on them, the system achieves sufficient measurement precision for its purpose while avoiding unnecessary complex processing steps
Data Source
AI summary
The present disclosure relates to an uplink summation method and device, and a distributed antenna system. The method comprises: acquiring uplink CPRI data streams of a channel of an AU or an EU in a system, performing bit width extension on the CPRI data streams, and performing full precision summation; extracting an orthogonal IQ signal in the CPRI data streams after summation, and determining a reference value and a detected value of the IQ signal so as to determine attenuation values corresponding to fast fading and slow amplification of the IQ signal; generating a gain table corresponding to CPRI data according to carrier mapping information of the system and the attenuation values; and shifting the IQ signal in the CPRI data streams according to the gain table, and truncating the shifted IQ signal with a preconfigured bit width.