Polar Coding for Beam Sweeping With Adjacent-Block LLR Combining
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Solution Overview
Problem
In 5G wireless communication systems, particularly in beam sweeping scenarios, receivers face challenges in combining signals from adjacent beams due to block-dependent time indices, which prevents direct addition of log-likelihood ratios (LLRs) from adjacent blocks, affecting signal reception and decoding efficiency.
Innovation Solution
The proposed solution involves encoding the time index separately using a second channel code of the same block length as the polar code for system information, allowing for superposition coding and easy combination of LLRs from adjacent blocks, enabling direct decoding of both the time index and system information without additional hypothesizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If beam sweeping is used to broadcast system information in 5G wireless communication systems, then signal coverage and power gain are improved, but the ability to combine signals from adjacent beams is degraded due to block-dependent time indices
Solution Approach 1:
The patent segments the information transmitted in beam sweeping into two distinct parts: time-varying components (time index, beam index) and time-invariant components (system information). The time-varying components are encoded separately using a second channel code, while the time-invariant components are encoded using a first channel code. This segmentation allows receivers to combine signals from adjacent beams by removing the time-varying components before combination, thereby resolving the contradiction between maintaining signal coverage through beam sweeping and enabling signal combination for improved reception.
2Loss of information
If time index is included in each beam's system information broadcast, then receivers can determine radio frame boundaries, but decoding complexity increases due to the need for additional hypothesizing
Solution Approach 1:
The patent extracts the time index (time-varying component) from the system information and encodes it separately using a second channel code, while the remaining system information (time-invariant component) is encoded using a first channel code. This extraction allows receivers to decode the time index independently without needing to hypothesize about its value, thereby reducing decoding complexity while still providing the necessary time synchronization information for determining radio frame boundaries.
3Measurement precision
If adjacent signal blocks contain different time-varying components, then each block carries accurate time information, but direct addition of log-likelihood ratios from adjacent blocks becomes impossible
Solution Approach 1:
The patent applies different encoding qualities to different parts of the transmitted information. The time-varying components (time index, beam index) are encoded with a second channel code that allows for easy removal and comparison, while the time-invariant system information is encoded with a first channel code. This local differentiation in encoding quality enables receivers to accurately identify and remove time-varying components from adjacent blocks before combining their log-likelihood ratios, thereby maintaining time index accuracy while enabling efficient signal combination.
Data Source
AI summary
According to some embodiments, a method in a wireless transmitter comprises: obtaining a first set of bits (comprising a non-time-varying component) for wireless transmission; concatenating a second set of bits (comprising a time-varying component (e.g., beam identifier)) to the first set of bits; encoding the concatenated first and second set of bits using a channel code; and transmitting the encoded bits to a wireless receiver. In some embodiments, transmitting the encoded bits to the wireless receiver comprises transmitting a first beam. The method may further comprise: concatenating a third set of bits (comprising a time-varying component (e.g., beam identifier)) to the first set of wireless bits; encoding the concatenated first and third set of bits using a channel code; and transmitting the encoded bits to a wireless receiver using a second beam.