Crest Factor Reduction Module Positioning in Distributed Antenna Systems
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Solution Overview
Problem
In distributed antenna systems, the implementation of crest factor reduction (CFR) modules at the front end of remote units increases complexity and cost, especially when multi-band signal processing is required, leading to significant challenges in managing signal degradation and RU complexity.
Innovation Solution
Positioning the CFR module optimally within the distributed antenna system, either in the hub unit or head-end unit, posterior to the mixing processing stage, to minimize signal degradation and reduce the complexity of remote units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CFR module is implemented at the front end of each remote unit, then the peak-to-average power ratio (PAPR) of signals is reduced, but the complexity and cost of the distributed antenna system increases significantly
Solution Approach 1:
The CFR module is extracted from the remote units and relocated to the hub unit. This centralizes the PAPR reduction functionality, eliminating the need for complex CFR implementations at each remote unit while maintaining the signal quality benefits. The hub unit, having greater processing capability, handles the CFR function centrally.
Solution Approach 2:
The CFR module is merged with the hub unit's existing signal processing functions. By combining the PAPR reduction capability with the central hub's mixing and signal distribution functions, the system achieves efficient signal processing without duplicating CFR functionality across multiple remote units, thereby reducing overall system complexity.
2Adaptability or versatility
If multi-band signal processing is performed at remote units, then service coverage is enhanced, but the complexity for implementing the RUs considerably increases
Solution Approach 1:
The system segments the multi-band signal processing functions between the hub unit and remote units. The hub unit handles complex mixing and CFR operations for multiple bands, while remote units focus on simpler signal distribution tasks. This functional segmentation allows multi-band support without overloading the remote units with excessive complexity.
Solution Approach 2:
The hub unit acts as an intermediary that performs complex multi-band signal processing before distributing signals to remote units. This intermediary approach allows remote units to maintain simplicity while the system as a whole achieves multi-band capability through the hub's processing capabilities.
3Productivity
If the CFR module is positioned at the front end of remote units, then signal processing is performed early in the transmission chain, but signal degradation occurs due to multiple processing stages
Solution Approach 1:
The CFR module is extracted from the remote units and positioned centrally in the hub unit. This eliminates the need for signals to pass through multiple remote unit processing stages, thereby reducing cumulative signal degradation while maintaining early PAPR reduction benefits in the overall signal chain.
Data Source
AI summary
A distributed antenna system includes a plurality of head-end units for each receiving mobile communication signals from at least one corresponding base station, a hub unit communicatively coupled to the plurality of head-end units, and a plurality of remote units communicatively coupled to the hub unit, wherein the hub unit configured to distribute the mobile communication signals received from each of the plurality of head-end units to the plurality of remote units, wherein each of the plurality of remote units is remotely disposed to transmit the distributed mobile communication signals to a terminal in service coverage, and wherein the hub unit includes a mixing processing stage configured to perform digital mixing processing on the mobile communication signals respectively received from the plurality of head-end units, and a crest factor reduction (CFR) module disposed posterior to the mixing processing stage, with respect to a signal transmission direction.