Wi‑Fi Packet Remapping for Robust HARQ Soft Combining
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Solution Overview
Problem
The IEEE 802.11 standard lacks support for Hybrid Automatic Repeat Request (HARQ), leading to difficulties in identifying and combining soft bits at the receiver due to corrupted address, sequence, and length fields during re-transmissions, especially in aggregated data frames.
Innovation Solution
Re-mapping critical control information within data packets to more robust bits in the modulation and coding scheme, ensuring reliable identification and combination of soft bits during re-transmissions by enhancing the robustness of receiver address, duration, and segment/fragment identification fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control information is transmitted using standard modulation and coding schemes, then transmission throughput is maintained, but reliability of control information during re-transmissions deteriorates due to bit corruption
Solution Approach 1:
The patent applies different robustness characteristics to different parts of the data packet. Specifically, control information bits (such as address, sequence number, and length fields) are mapped to more robust signal constellation points that are less susceptible to errors, while data payload bits use standard modulation mapping. This local differentiation ensures that critical control information maintains high reliability during re-transmissions without significantly impacting overall throughput.
2Reliability
If soft combining is implemented at the receiver, then error correction capability is improved, but ability to identify and combine soft bits deteriorates due to corrupted control fields
Solution Approach 1:
The patent performs preliminary protection of control information by mapping these bits to more robust constellation points before transmission. This preliminary action ensures that when re-transmissions occur, the control fields (address, sequence number, length) remain sufficiently intact to enable the receiver to correctly identify and combine soft bits, thus maintaining measurement precision for soft bit identification.
3Reliability
If robust mapping is applied to control information, then identification reliability is improved, but complexity of transmission processing increases
Solution Approach 1:
The patent changes the mapping parameter (signal constellation assignment) for control information bits to achieve higher robustness. Instead of using standard uniform mapping, control bits are assigned to specific constellation points with larger minimum distances or more favorable error characteristics. This parameter change improves identification reliability while maintaining compatibility with existing modulation and coding frameworks, thus limiting the increase in processing complexity.
Data Source
AI summary
A transceiver device includes a controller arranged to identify a first set of control information within the data packet, and to re-map the data packet such that the first set of control information is mapped on bits known to be more robust. The transceiver device further includes a transmitter arranged to transmit the re-mapped data packet. The first set of control information holds information which enables for identification to combine soft bits from repeated transmissions at a receiver of the packet. The bits known to be more robust have more distinct value distribution in signal space of a used modulation and coding scheme than other bits. The transceiver device is arranged to transmit a data packet. A corresponding method, computer program, access point and station are also disclosed.