Radio Receiver Channel Condition Detection for Rake-Equalizer Switching

Solution Overview

Problem

Conventional CDMA mobile radio receivers face performance degradation due to Multiple Access Interference (MAI) and channel estimation errors, especially in high-speed downlink packet access scenarios, as they struggle to distinguish between single-ray and low delay spread channel profiles, leading to sub-optimal performance in selecting between rake and equalizer processing.

Innovation Solution

A method and receiver system that identify n-ray channel conditions by estimating channel taps, filtering signal and disturbance power, determining the strongest taps, and generating comparison parameters to select between rake and equalizer processing based on threshold values, optimizing receiver performance for specific propagation conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If channel equalization is used to restore code orthogonality in multipath conditions, then performance advantage is achieved over rake processing, but implementation complexity increases significantly

Engineering Contradiction:

Improvereceiver performanceVSAvoidimplementation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system dynamically adapts the signal processing mode by detecting channel conditions (single-ray vs. multipath) and switching between rake processing and channel equalization accordingly. This dynamic adaptation allows the receiver to optimize performance for each specific propagation scenario without permanently incurring the complexity of channel equalization.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the processing parameter (signal processing algorithm) based on detected channel conditions. By monitoring channel characteristics and adjusting the processing mode, the system achieves performance optimization without permanent complexity increase.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a channel equalizer is used to improve performance in multipath conditions, then superior performance is achieved, but the system becomes less efficient under single-ray propagation conditions where rake receiver is sufficient

Engineering Contradiction:

Improvereceiver performanceVSAvoidprocessing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adapts the signal processing mode by detecting channel conditions (single-ray vs. multipath) and switching between rake processing and channel equalization accordingly. This dynamic adaptation allows the receiver to optimize performance for each specific propagation scenario without permanently incurring the complexity of channel equalization.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the processing parameter (signal processing algorithm) based on detected channel conditions. By monitoring channel characteristics and adjusting the processing mode, the system achieves performance optimization without permanent complexity increase.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional rake processing is used in high data rate HSDPA scenarios, then device complexity remains manageable, but performance degradation occurs due to loss of code orthogonality from multipath propagation

Engineering Contradiction:

Improvedevice complexityVSAvoidreceiver performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system dynamically adapts the signal processing mode by detecting channel conditions (single-ray vs. multipath) and switching between rake processing and channel equalization accordingly. This dynamic adaptation allows the receiver to optimize performance for each specific propagation scenario without permanently incurring the complexity of channel equalization.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The channel condition detector acts as an intermediary that monitors propagation conditions and determines the appropriate processing mode. This intermediary component enables the system to select the optimal processing algorithm based on real-time channel characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8934520B2Radio receiver in a wireless communication system

Publication Date: 2015.01.13 ICERA INC

AI summary

A method, receiver and program for processing radio signals to identity an n-ray channel condition. The method comprises: receiving signal samples and estimating a plurality of channel taps from the samples; estimating for each of the channel taps a signal power and a disturbance power; filtering the signal power to provide a filtered signal power quantity; filtering the disturbance power to provide a filtered disturbance power quantity; using the filtered power quantities to determine n strongest channel taps; generating first and second comparison parameters using the strongest channel taps and at least one other channel tap; providing a comparison result based on the first and second comparison parameters and a threshold value, and; identifying an n-ray channel condition from the comparison result.