Compact DCI Size Alignment for 5G Waveform Switching
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Solution Overview
Problem
In 5G communication systems, dynamic waveform switching between DFT-S-OFDM and CP-OFDM causes misalignment of downlink control information (DCI) payload sizes, leading to decoding challenges for user equipment (UE) due to unclear waveform types, which affects network performance and compliance with current 3GPP specifications.
Innovation Solution
A method and apparatus for compact DCI size alignment, where zero-padded bits are applied based on the waveform type indicated by the most recent DCI message scrambled by a cell RNTI, allowing UEs to determine the positions of zero-padded bits and partition waveform-dependent fields accordingly, ensuring alignment without modifying current 3GPP protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic waveform switching is implemented between DFT-S-OFDM and CP-OFDM, then system adaptability and service support are improved, but DCI payload size alignment deteriorates causing decoding challenges
Solution Approach 1:
The patent applies preliminary action by having the UE store and recall the waveform type from the most recent DCI message scrambled by C-RNTI before decoding the current DCI message scrambled by CS-RNTI. This pre-established knowledge allows the UE to correctly determine zero-padding positions and WDF sizes without real-time ambiguity, resolving the decoding reliability issue while maintaining waveform switching adaptability
2Reliability
If DCI payload sizes are aligned for all waveform types, then decoding reliability is improved, but DCI overhead increases due to zero-padding
Solution Approach 1:
The patent applies local quality by applying zero-padding selectively only to specific fields (non-WDFs and portioned WDFs) rather than uniformly to the entire DCI payload. The zero-padding is applied locally at precise positions determined by the recalled waveform type, ensuring alignment where needed while minimizing unnecessary padding overhead in other regions
Solution Approach 2:
The patent segments the DCI payload into distinct components: non-waveform-dependent fields (non-WDFs), waveform-dependent fields (WDFs), and zero-padding portions. This segmentation allows independent handling of each component, applying alignment only where necessary and enabling efficient identification of zero-padding positions without affecting the entire payload structure
3Manufacturing precision
If zero-padding is applied to align DCI sizes, then DCI size alignment is improved, but determination of zero-padding positions becomes complex
Solution Approach 1:
The patent uses feedback by having the UE recall the waveform type information from previously decoded DCI messages scrambled by C-RNTI. This feedback loop provides the necessary context to determine zero-padding positions in the current CS-RNTI scrambled DCI message, reducing complexity compared to attempting to determine positions without such feedback
Solution Approach 2:
The patent applies preliminary action by pre-storing the waveform type from the most recent C-RNTI scrambled DCI message. This preliminary establishment of waveform type knowledge enables straightforward determination of zero-padding positions when decoding subsequent CS-RNTI scrambled messages, avoiding complex real-time calculations
Data Source
AI summary
A method includes receiving, from a network element, a first downlink control information (DCI) message, wherein the first DCI message comprises a plurality of DCI fields. The method also includes determining a first radio network temporary identifier (RNTI) type of a first RNTI that is used for scrambling cyclic redundancy check (CRC) bits of the first DCI message. The method also includes determining a waveform type indicated by a second DCI message, wherein the second DCI message is a most recent DCI message received by the apparatus prior to the first DCI message, and wherein CRC bits of the second DCI message are scrambled by a second RNTI, and wherein the second RNTI is a cell RNTI (C-RNTI). The method also includes decoding the first DCI message based at least in part on the first RNTI type and the waveform type.