HARQ LLR Compression for Lower Memory Chip Area
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Solution Overview
Problem
High-performance HARQ operations in wireless communication systems require significant memory space for storing received packets, which is costly in terms of chip area, especially with the massive growth in traffic volume due to 5G wireless communications.
Innovation Solution
The apparatus implements a method that reduces memory usage by using a HARQ scheme with a processor, memory, and RF unit, which compresses and decompresses log likelihood ratio (LLR) values using a compression codebook based on signal quality and parity check matrix, allowing for efficient storage and retransmission of packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ operations store received packets in memory for robust error control, then reliability is improved, but chip area increases
Solution Approach 1:
The patent extracts only the essential information needed for HARQ operations (LLR values and signal quality indicators) from the complete received packets, storing only these extracted elements in memory rather than the full packets. This reduction in stored data directly reduces the memory size and chip area required while maintaining the reliability needed for error control through selective information retention.
Solution Approach 2:
Instead of storing complete packets and processing them fully, the patent inverts the approach by storing only compressed representations (LLR values and signal quality) and performing decomposition only when needed for retransmission. This inversion of the storage strategy reduces memory requirements while preserving the ability to maintain robust error control when retransmissions are required.
2Area of stationary object
If memory size is reduced to decrease chip area, then chip area is reduced, but HARQ operation performance may deteriorate
Solution Approach 1:
The patent changes the parameters of stored data from complete packets to compressed representations consisting of LLR values and signal quality indicators. This parameter transformation reduces the amount of memory required while preserving the essential information needed for HARQ operations, thereby maintaining performance despite reduced memory size.
Solution Approach 2:
The patent applies different storage strategies to different types of information: storing only LLR values and signal quality indicators in memory rather than complete packets. This localized optimization of storage quality reduces overall memory requirements while maintaining the critical information needed for HARQ performance, achieving a balance between chip area and operational effectiveness.
Data Source
AI summary
A method reducing amount of memory utilized by hybrid automatic repeat request (HARQ) operations is disclosed. When an apparatus employing the method receives an LDPC encoded packet, the apparatus firstly estimates a signal quality value of the received packet, and performs an LDPC decoding algorithm on the received packet. If the received packet is not successfully decoded by the apparatus, the received and decoding-failed packet is compressed in order to reduce bit-width, and the compressed packet is stored in a memory device for later HARQ operations. The apparatus employing the method is also disclosed.