PUSCH UCI Multiplexing via DAI Value Determination
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Solution Overview
Problem
In New Radio (NR) Rel-15, the ambiguity between the gNodeB and the User Equipment (UE) regarding which Physical Uplink Shared Channels (PUSCHs) have uplink control information (UCI) multiplexed leads to complexity in decoding, especially when multiple PUSCHs overlap with the Physical Uplink Control Channel (PUCCH), causing incorrect decoding and increased implementation complexity.
Innovation Solution
A method where the User Equipment (UE) determines, based on Downlink Assignment Index (DAI) values, which PUSCH to multiplex UCI on, ensuring no more than one PUSCH has a DAI value not equal to four, thereby minimizing ambiguity and correctly identifying the PUSCH with UCI, even in cases of overlapping channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple PUSCHs are scheduled to overlap with PUCCH, then the system can support more uplink transmissions and improve resource utilization, but ambiguity arises between gNB and UE about which PUSCH has UCI multiplexed, increasing decoding complexity
Solution Approach 1:
The patent uses the DAI (Downlink Assignment Index) parameter to differentiate between multiple PUSCHs. By setting at most one PUSCH with DAI value not equal to four, the system creates a unique identifier that resolves ambiguity about which PUSCH carries multiplexed UCI, thereby reducing decoding complexity while maintaining support for multiple overlapping PUSCH transmissions
Solution Approach 2:
The DAI value acts as an intermediary indicator that mediates between the gNB's scheduling decision and the UE's transmission behavior. This intermediary parameter enables both parties to independently determine which PUSCH should carry multiplexed UCI without direct communication, reducing the need for complex decoding procedures
2Reliability
If the gNB performs double decoding for all overlapping PUSCHs to resolve ambiguity, then correct UCI decoding can be achieved, but implementation complexity and processing time increase significantly
Solution Approach 1:
The DAI value is predetermined and included in the scheduling DCI before transmission occurs. This preliminary indication allows the UE to proactively multiplex UCI on the correct PUSCH without requiring the gNB to perform time-consuming trial decoding, thus achieving reliable UCI decoding while minimizing processing time
3Adaptability or versatility
If DAI field uses 2 bits with value 4 indicating either 0 or 4*n HARQ-ACK bits, then the encoding space is efficiently utilized, but confusion arises in determining the actual number of HARQ-ACK bits
Solution Approach 1:
The patent applies different local meanings to the DAI value based on context: when DAI equals four, it specifically indicates that no UCI is multiplexed on that PUSCH. This local differentiation within the encoding scheme eliminates the ambiguity of whether value 4 means 0 bits or 4*n bits, while preserving the overall flexibility of the 2-bit encoding format
Data Source
AI summary
Disclosed are methods and apparatus for multiplexing of uplink control information on uplink data channels in wireless communication. It may be determined that transmission of a plurality of physical uplink shared channels (PUSCHs) are scheduled. The transmission of the plurality of PUSCHs may overlap with transmission of an uplink control information (UCI). At most one of the plurality of PUSCHs on to which the UCI is multiplexed may be determined based on a Downlink Assignment Index (DAI) value. The plurality of PUSCHs may be set with no more than one PUSCH having the DAI value not equal to four. Thereafter, the determined PUSCH is transmitted with the UCI multiplexed on it.