Shared Downlink Equalizer for Ripple Reduction in Distributed Antenna Systems

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Solution Overview

Problem

Distributed antenna systems (DAS) face challenges in minimizing downlink and uplink ripples due to the inherent non-linearity of bandpass filters, which can distort communications signals and require multiple equalizers, increasing cost and complexity.

Innovation Solution

A system where a downlink equalizer is shared between a downlink simplex port and a duplex port in a radio interface module, with the equalizer configured to go through multiple states to optimize ripple reduction by testing and recording ripples at each state, allowing it to function based on the state with the smallest ripple, thereby reducing the number of equalizers needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple equalizers are used to minimize downlink and uplink ripples, then signal quality is improved, but device complexity and cost increase

Engineering Contradiction:

Improvesignal qualityVSAvoidnumber of equalizers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple equalizer functions into a single shared equalizer that can be dynamically configured. The equalizer is shared between downlink simplex port and duplex port, and can be switched between different operational modes (downlink equalization mode and uplink equalization mode) based on signal direction requirements, thereby reducing the total number of equalizers while maintaining signal quality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The equalizer is designed with dynamic reconfigurability, allowing it to adapt its parameters and operational state based on real-time signal conditions. The equalizer can be dynamically switched between serving downlink simplex port, serving duplex port, or being in a high-state/low-state configuration, enabling a single equalizer to perform multiple functions that previously required separate dedicated equalizers.

Inventive Principle:

Principle #15Dynamics

2Reliability

If bandpass filters with higher order are used to reduce ripples, then signal distortion is reduced, but device complexity and cost increase

Engineering Contradiction:

Improvesignal distortionVSAvoidfilter order

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of increasing the fixed order of bandpass filters, the patent employs digitally controlled equalizers that dynamically adjust their parameters (such as gain, phase, and frequency response) to compensate for filter-induced ripples. This allows for ripple reduction through software-controlled parameter optimization rather than hardware complexity increase.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/approach of using higher-order analog filters with a digital signal processing approach. Digital equalizers use algorithms to correct frequency response deviations, substituting complex analog filter designs with programmable digital systems that achieve similar or better ripple reduction with less hardware complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If separate equalizers are allocated for downlink simplex port and duplex port, then each port's ripple is optimized, but cost and device complexity increase

Engineering Contradiction:

Improveripple optimizationVSAvoidnumber of equalizers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent designs a universal equalizer that can serve multiple ports and functions. The same equalizer unit can be configured to optimize ripple for downlink simplex port, duplex port, or both simultaneously through dynamic parameter adjustment and mode switching, eliminating the need for separate dedicated equalizers for each port while maintaining optimization performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The equalizer is divided into independently controllable segments or stages that can be selectively activated or configured based on which port requires optimization. This segmentation allows the single equalizer to adaptively allocate its processing resources to different ports as needed, providing specialized optimization for each port without requiring physically separate equalizer units.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9692585B2Equalizing distributed antenna system equipped with multiple base station interface ports

Publication Date: 2017.06.27 ANI ACQUISITION SUB LLC

AI summary

Optimizing ripple reductions in equalizers shared between multiple interface ports in a distributed antenna system (DAS). In one aspect, a downlink equalizer is shared between a downlink simplex port and a duplex port in a radio interface module(s) (RIM(s)) in the DAS. In another aspect, to optimize ripple reduction in the downlink equalizer, the downlink equalizer is configured to go through a plurality of downlink equalizer states that each can generate a downlink equalizer frequency response affecting downlink ripple of the RIM(s). At each of the downlink equalizer states, a test signal is provided to the downlink equalizer and a corresponding downlink ripple of the RIM(s) is recorded. When all of the downlink equalizer states are evaluated based on the test signal, the downlink equalizer is configured to function based on the downlink equalizer state associated with the smallest downlink ripple of the RIM(s).