Receiver Soft Combining Without HARQ Standard Modification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The 802.11 standard lacks support for Hybrid Automatic Repeat Request (HARQ) mechanisms, making it difficult for receivers to identify the transmitter, differentiate between collisions and decoding errors, and combine soft values effectively, especially in cases of CRC failures.
Innovation Solution
A receiver and method that perform a hard decision on soft values to determine the transmitter and identify retransmissions, allowing for the combination of soft values from previous transmissions without modifying the 802.11 standard, and include features to detect collisions and apply beam forming patterns to improve decoding accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ mechanism is implemented to combine soft values of previous transmissions, then the probability of correct decoding is improved, but the device complexity increases due to memory allocation and transmitter identification requirements
Solution Approach 1:
The system uses the existing MAC header and CRC fields already present in the 802.11 standard to carry HARQ identification information. The receiver serves itself by extracting transmitter ID and retransmission status from the MAC header without requiring separate HARQ control fields, thus avoiding additional complexity while enabling soft combining
Solution Approach 2:
The MAC header and CRC fields are made multi-functional: they simultaneously serve their original 802.11 purposes and carry HARQ identification information. This allows the same data structures to support both standard 802.11 operations and HARQ soft combining functionality without adding separate dedicated structures
2Ease of operation
If hard decision is performed on soft values to identify transmitter and retransmission status, then the ease of operation is improved, but the manufacturing precision decreases due to information loss
Solution Approach 1:
The processing is segmented into two distinct stages: first, hard decision is applied only to the MAC header portion to extract identification information (transmitter ID, retransmission status); second, soft combining is applied to the payload portion using the original soft values. This segmentation allows easy identification while preserving soft value accuracy for the actual data combining operation
3Reliability
If CRC check is performed on each received packet, then the reliability is improved, but the loss of time increases due to repeated checking of corrupted packets
Solution Approach 1:
The system performs preliminary soft combining of multiple received packets before performing the final CRC check. By combining soft values from multiple transmissions and then performing a single CRC verification on the combined result, the system reduces the number of times corrupted packets must be individually processed, thereby reducing time loss while maintaining reliable error detection
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention proposes a receiver (1) and method for decoding data packets. A receiving unit (5) of the receiver (1) receives a data packet P1, which contains a MAC header. A soft decoder (3) of the receiver (1) decodes the data packet P1 to obtain soft values of the data packet P1, and an error checking module (2) of the receiver performs a cyclic redundancy check, CRC, on the data packet P1. If the CRC on the data packet P1 fails, a hard decoder (4) of the receiver (1) performs a first hard decision on the soft values of the data packet P1 corresponding to the MAC header of the data packet P1, and a controller (8) of the receiver (1) determines based on the result of the first hard decision, whether soft values of a previous transmission of the data packet P are stored in a memory (6) of the receiver (1), and combines said stored soft values with the soft values of the data packet P1 to obtain combined soft values. Finally, the error checking module (2) performs a CRC based on the combined soft values.