LTE PDCCH Encoding with Modified Circular Buffer Rate Matching
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Solution Overview
Problem
In LTE telecommunications systems, Physical Downlink Control Channel (PDCCH) detection errors occur due to aggregation level confusion caused by overlapping search spaces and circular buffer-based rate matching, leading to incorrect uplink ACK/NACK resource location and reduced downlink throughput.
Innovation Solution
Modifying the size of the circular buffer by excluding at least one coded bit to prevent aggregation level confusion, ensuring unambiguous encoding of PDCCH, which reduces the likelihood of incorrect aggregation level selection and improves detection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If circular buffer-based rate matching is used for PDCCH encoding, then coding efficiency is improved, but aggregation level confusion occurs leading to detection errors
Solution Approach 1:
The patent extracts the problematic circular buffer-based rate matching process and replaces it with a modified rate matching approach that excludes certain coded bits from the circular buffer. This extraction of the harmful mechanism eliminates the aggregation level confusion while preserving the beneficial coding efficiency.
Solution Approach 2:
The patent changes the rate matching parameter by modifying how coded bits are placed in the circular buffer. Specifically, it changes the rate matching rule to exclude bits at positions that would create ambiguous aggregation patterns, thereby changing the structural parameter of the encoding process to prevent detection errors.
2Productivity
If search spaces for different aggregation levels overlap, then resource utilization is improved, but detection accuracy deteriorates due to ambiguous PDCCH candidates
Solution Approach 1:
The patent converts the harmful effect of overlapping search spaces into a beneficial outcome by modifying the rate matching process. The same overlapping structure is retained for resource efficiency, but the modified encoding ensures that overlapping regions do not create ambiguous detection scenarios, thus converting the potential harm into acceptable operation.
3Adaptability or versatility
If multiple PDCCH candidates are monitored at different aggregation levels, then coverage is improved, but false detection probability increases
Solution Approach 1:
The patent applies preliminary action by modifying the encoding process before transmission to prevent false detections. By changing the rate matching rules in advance, the system ensures that when the UE monitors multiple aggregation levels, the modified bit patterns prevent false CRC matches, thus preliminarily eliminating the cause of false detections before they can occur.
Data Source
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AI summary
A system, method and node for unambiguous encoding of Physical Downlink Control Channel (PDCCH) channels in a Long Term Evolution (LTE) telecommunications system to remove detection errors. The method includes the step of modifying a size of a circular buffer by excluding at least one coded bit from the circular buffer. The circular buffer collects interleaved bits from a PDCCH payload having a plurality of bits. The PDCCH payload is encoded with a convolutional code. The bits of the PDCCH payload are then interleaved. The interleaved bits are collected into the modified circular buffer. The bits are then selected from the modified circular buffer for transmission.