HARQ Soft Combining with Dynamic Bit-Width Buffering
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Solution Overview
Problem
Conventional Hybrid Automatic Repeat-Request (HARQ) with soft combining techniques suffer from information loss due to saturated addition, particularly in multiple repeated transmissions, which limits the accuracy of data recovery in wireless communication systems.
Innovation Solution
Implementing HARQ with soft combining using a buffer of sufficient width to store combined soft bit values without saturated addition, and dynamically transforming these values to match the bit width required by the decoder input based on the maximum absolute soft bit value stored, allowing for more accurate data recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If saturated addition is used for soft combining in HARQ, then buffer bit width can be reduced and calculations simplified, but information loss occurs especially in multiple repeated transmissions
Solution Approach 1:
The patent implements dynamic bit width adjustment for the buffer based on the magnitude of accumulated soft bit values. The buffer width is not fixed but adapts to the actual data requirements, expanding when larger values are detected and contracting when smaller values suffice. This dynamic approach prevents information loss while avoiding the need for consistently large buffer allocations.
Solution Approach 2:
The patent changes the parameter of buffer bit width from a static fixed value to a dynamic value that varies based on the maximum absolute soft bit value accumulated during HARQ combining. This parameter change allows the system to maintain sufficient precision for accurate decoding while reducing overall complexity when smaller buffer widths are adequate.
2Loss of information
If a buffer of sufficient width is used to store combined soft bit values without saturated addition, then information loss is reduced, but device complexity increases
Solution Approach 1:
The system dynamically adjusts the buffer bit width based on the maximum absolute soft bit value detected during combining operations. When larger values are accumulated, the buffer width increases to prevent saturation and information loss. When smaller values suffice, the buffer width decreases, reducing complexity. This dynamic adaptation resolves the contradiction between preventing information loss and minimizing device complexity.
Solution Approach 2:
The patent implements parameter change by varying the buffer bit width according to the magnitude of soft bit values being combined. Instead of using a fixed large buffer width that always prevents information loss but maximizes complexity, the system changes the buffer width parameter to match the actual data requirements, achieving optimal balance between accuracy and complexity.
3Measurement precision
If soft combining is performed without saturated addition, then combining accuracy improves, but buffer width requirements increase
Solution Approach 1:
The patent uses dynamic buffer width adjustment to meet the varying storage requirements of accurate soft combining. The buffer width expands when larger soft bit values are detected during combining operations, ensuring sufficient precision is maintained, and contracts when smaller values are sufficient, reducing the complexity burden. This dynamic approach enables high combining accuracy without consistently requiring large buffers.
Solution Approach 2:
The system changes the buffer width parameter dynamically based on the maximum absolute soft bit value accumulated during combining. This parameter change allows the buffer to provide sufficient width for accurate combining when needed while avoiding excessive complexity when smaller buffers suffice, achieving optimal balance between precision and device complexity.
Data Source
AI summary
In one embodiment, a method for data communication may include receiving a first set of soft bit values in a Hybrid Automatic Repeat-Request (HARQ) buffer using a first bit width. The method may also include soft combining the first set of soft bit values with a second set of soft bit values to obtain a set of combined soft bit values. The method may also include transforming the set of combined soft bit values from the first bit width to a decoder input bit width to obtain a set of transformed soft bit values.