Soft Information Compression for LTE Decoding

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Solution Overview

Problem

In wireless communication systems using the 3GPP LTE protocol, storing soft information values for failed decoding attempts results in significant storage and bandwidth requirements, which can impose a substantial load on memory resources, especially in high data rate systems.

Innovation Solution

The method involves compressing soft information values before storage, reducing memory size and bandwidth requirements, while maintaining system throughput performance by using either internal or external memory, and decompressing them for combined decoding attempts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If soft information values are stored without compression, then decoding accuracy is maintained, but memory size and bandwidth requirements increase significantly

Engineering Contradiction:
Improvedecoding accuracyVSAvoidmemory size
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by compressing the soft information values from their original format (e.g., 8-bit LLR values) to a compressed representation that requires less storage space. This compression reduces the quantity of data stored while maintaining the essential information needed for accurate decoding, thus resolving the contradiction between memory size and decoding accuracy.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a compressed copy of the soft information values that can be stored efficiently in memory. Instead of storing the full-precision soft information, a compressed representation is created and stored, which can later be decompressed and combined with subsequent transmissions to achieve accurate decoding without requiring proportional memory resources.

Inventive Principle:
Principle #26Copying

2Quantity of substance

If soft information values are compressed before storage, then memory size and bandwidth requirements are reduced, but system complexity increases

Engineering Contradiction:
Improvebandwidth usageVSAvoidprocessing complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing compression of soft information values immediately when they are generated, before storage or further processing. This upfront compression step reduces the data volume that needs to be managed throughout the subsequent HARQ process, making the overall system more efficient despite the added compression step.

Inventive Principle:
Principle #10Preliminary action

3Quantity of substance

If compressed soft information values are stored, then memory costs are reduced, but decompression and combining operations require additional processing time

Engineering Contradiction:
Improvememory capacityVSAvoidprocessing time
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The patent uses parameter changes through compression and decompression operations that transform the soft information values between compressed and uncompressed formats. The compression ratio and decompression algorithm are designed to minimize processing overhead while achieving significant memory savings, thus balancing the trade-off between storage capacity and processing time.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9197365B2Decoding a coded data block
Publication Date: 2015.11.24 NVIDIA CORP
  • US9197365B2 patent drawing
  • US9197365B2 patent drawing
  • US9197365B2 patent drawing

AI summary

Method, receiver and computer program product for decoding a coded data block received at the receiver are disclosed. A first plurality of coded data bits representing the coded data block are received. First soft information values are determined corresponding to respective ones of the received first plurality of coded data bits, wherein each of the soft information values indicates a likelihood of a corresponding coded data bit having a particular value. An attempt is made to decode the coded data block using the first soft information values. The first soft information values are compressed. The compressed first soft information values are stored in a data store. A second plurality of coded data bits representing the coded data block is received and second soft information values corresponding to respective ones of the received second plurality of coded data bits are determined. The compressed first soft information values are retrieved from the data store and decompressed. The decompressed first soft information values are combined with the second soft information values, and an attempt is made to decode the coded data block using the combined soft information values.