Iterative Trellis Equalization for Interference Mitigation

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Solution Overview

Problem

Current signal equalization methods for payload channels in the presence of interference channels are computationally complex, leading to high DSP load and making practical mobile radio use challenging, especially when considering multiple access interference and multipath propagation.

Innovation Solution

The method involves processing the trellis diagrams for both the payload and interference channels separately over cohesive time intervals, allowing for iterative equalization without altering the hardware accelerator, using a software module to correct symbols and reduce computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If joint Viterbi equalization is performed for both payload and interference channels, then interference mitigation is improved, but device complexity and DSP load increase exponentially

Engineering Contradiction:

Improvesignal detection accuracyVSAvoidequalizer complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The joint equalization problem is segmented into two separate sequential equalizations: first for the payload channel, then for the interference channel. This divides the exponentially complex joint processing into two manageable separate processing stages, reducing overall computational complexity while maintaining interference mitigation effectiveness

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The payload channel is equalized first to obtain preliminary symbol estimates, which are then used as input for the interference channel equalization. This preliminary action allows the interference channel processing to benefit from already-separated payload symbols, improving overall detection accuracy without requiring simultaneous joint processing

Inventive Principle:

Principle #10Preliminary action

2Productivity

If separate trellis processing is used for payload and interference channels, then DSP load is reduced, but interference mitigation effectiveness may be compromised

Engineering Contradiction:

Improveprocessing efficiencyVSAvoidinterference cancellation accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The method uses feedback by taking the equalized payload symbols from the first processing stage and using them as known inputs for the second interference channel equalization stage. This feedback mechanism ensures that the separate processing stages are coordinated and maintain interference mitigation effectiveness

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The equalized payload symbols serve as an intermediary between the two separate equalization processes. By using these intermediate results from the payload channel equalization as inputs for interference channel processing, the method bridges the two separate operations and maintains overall system effectiveness

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7372923B2Method for equalization of a payload signal, taking into account an interference source

Publication Date: 2008.05.13 INTEL CORP

AI summary

In a method for equalization of a signal which is transmitted via a payload channel taking into account at least one interference channel, the trellis diagram for the interference channel is processed over an interval of time units. The symbols received in the interval of time units are then corrected by means of information which has been obtained during the processing of the trellis diagram for the interference channel. The trellis diagram for the payload channel is then processed over the same interval of time units, using the corrected symbols.