Polar-Coded HARQ Bit Relocation for Incremental Channel Polarization
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Solution Overview
Problem
Current wireless communication systems, particularly in LTE and NR technologies, face challenges in improving spectral efficiency and bit reliability during retransmissions in HARQ processes, as they lack the ability to dynamically adjust bit positions based on channel conditions, leading to suboptimal performance in multiple-access technologies.
Innovation Solution
The implementation of a polar coded hybrid automatic repeat request (HARQ) with incremental channel polarization, which involves performing a first polar code encoding process and generating subsequent transmissions by relocating bits from less reliable to more reliable positions using a channel transform matrix, allowing for flexible code length and rate-matching schemes based on previous transmission data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bits are transmitted in fixed positions during HARQ retransmissions, then system complexity is reduced, but bit reliability deteriorates due to inability to adapt to channel conditions
Solution Approach 1:
The patent pre-calculates and stores channel transform matrices for different transmission rounds before actual data transmission. These matrices are computed offline based on channel characteristics, so that during real-time HARQ operations, the system can directly apply these pre-prepared transforms to relocate bits from unreliable to reliable positions without performing complex real-time calculations, thus improving bit reliability while keeping implementation complexity manageable
Solution Approach 2:
The system dynamically changes the channel transform parameters (specifically the transform matrix) based on the transmission round number. Each transmission round uses a different pre-determined transform matrix that adapts to the cumulative channel conditions, allowing bits to be progressively relocated to more reliable positions across retransmissions without requiring complex real-time parameter adjustment
2Productivity
If channel transform is calculated based on previous transmissions, then spectral efficiency is improved through adaptive bit relocation, but processing time increases
Solution Approach 1:
Channel transform matrices are pre-calculated for all expected transmission rounds before actual data transmission begins. This offline preparation eliminates the need for time-consuming real-time calculations during HARQ retransmissions, allowing the system to achieve adaptive bit relocation and improved spectral efficiency without incurring additional processing time delays
Solution Approach 2:
The system employs dynamic bit position relocation through different pre-determined channel transform matrices for each transmission round. This dynamic adaptation to channel conditions across retransmissions improves spectral efficiency by placing bits in progressively more reliable positions, while the pre-computed nature of the transforms ensures that the adaptivity is achieved without real-time processing overhead
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a wireless communication device may perform a first polar code encoding process on a first transmission of a hybrid automatic repeat request (HARQ) process; generate a second transmission of the HARQ process by relocating a portion of bits in less reliable positions of the first transmission to more reliable positions of the second transmission of the HARQ process, wherein the less reliable positions and the more reliable positions are evaluated based at least in part on a channel transform, wherein the channel transform is based at least in part on the first transmission, the second transmission, the first polar encoding process and a second polar encoding process associated with the second transmission; and transmit the second transmission of the HARQ process. Numerous other aspects are provided.