Receiver Interference Cancellation for HARQ Decoding
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Solution Overview
Problem
Current broadband single carrier digital communications receivers face challenges in interference cancellation, particularly in severe noise or fading conditions, where received information bits may remain corrupted despite channel decoding, and existing Hybrid-ARQ solutions are limited to specific types, such as chase combining.
Innovation Solution
A method and device for decoding transmissions that perform interference cancellation on multiple received data sets, allowing for incremental redundancy HARQ, by deriving and combining soft coded bit estimates, regenerating symbol estimates, and iteratively canceling interference until correct decoding or a maximum number of iterations is reached, applicable to both chase combining and incremental redundancy HARQ.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel equalization and channel decoding are employed to counteract inter-symbol interference, then communication reliability is improved, but in severe noise or fading conditions, received information bits remain corrupted and require retransmission
Solution Approach 1:
The patent combines multiple received transmissions (first transmission and retransmission) by deriving received symbols from both, converting them to soft coded bit estimates, and combining these estimates before decoding. This merging of multiple transmissions allows the receiver to accumulate signal energy and improve decoding accuracy, reducing the need for additional retransmissions and thereby reducing time loss.
Solution Approach 2:
The patent implements an iterative process where the receiver decodes combined soft coded bit estimates, checks for correct decoding, and if incorrect, performs interference cancellation on the received data and repeats the decoding process. This feedback mechanism allows the system to progressively improve decoding accuracy through multiple iterations, reducing the need for external retransmissions.
2Adaptability or versatility
If soft combining of received coded bits is performed over multiple retransmissions in a soft-coded-bit buffer, then hybrid-ARQ performance is improved, but existing solutions are limited to chase combining HARQ only
Solution Approach 1:
The patent creates a universal interference cancellation method that works with both chase combining HARQ and incremental redundancy HARQ. The method derives received symbols from multiple transmissions, converts them to soft coded bit estimates, and combines them before decoding. This universal approach removes the limitation of existing solutions that only work with chase combining, thereby improving adaptability while maintaining reliability through effective interference cancellation.
Solution Approach 2:
The patent implements a dynamic iterative process where interference cancellation is performed on received data, and the process repeats with updated estimates until correct decoding is achieved or a maximum number of iterations is reached. This dynamic adaptation allows the system to effectively handle different HARQ types and varying channel conditions, improving both versatility and reliability.
3Measurement precision
If interference cancellation is performed on received data in the antenna buffer, then decoding accuracy is improved, but the complexity of the receiver device increases
Solution Approach 1:
The patent performs interference cancellation on the received data stored in the antenna buffer before the decoding process. By preliminarily removing interference from the received signals, the subsequent decoding operation works with cleaner data, improving decoding accuracy. This preliminary action is integrated into the existing receiver structure, minimizing additional complexity while achieving significant accuracy improvements.
Data Source
AI summary
A method, performed in a receiver device, for decoding transmissions of a set of coded information bits from a transmitter. The method includes deriving received symbols from first received data and second received data. The received symbols are converted to sets of soft coded bit estimates. The sets of soft coded bit estimates are combined to form a combined set of soft coded bit estimates. The combined set of soft coded bit estimates are decoded to form a set of soft information bit estimates. The set of soft information bit estimates are converted to form a set of binary bits. A determination is made whether the set of binary bits has been correctly or incorrectly decoded. Interference cancellation is performed on the received data, and the method is repeated until either the set of binary bits has been correctly decoded or a predefined maximum number of iterations is reached.