Variable Bitwidth DAI for Multi-PDSCH Miss Detection
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Solution Overview
Problem
Current wireless communication systems face challenges in reliably detecting missed downlink transmissions due to the limited bitwidth of the downlink assignment index (DAI) field, which becomes unreliable when more than a certain number of downlink control information (DCI) messages are missed.
Innovation Solution
The system employs a variable bitwidth for the downlink assignment index in DCI messages, allowing for enhanced miss detection by using a multi-physical downlink shared channel (PDSCH) format, DCI format, or carrier-specific bitwidth configurations, enabling accurate detection of missed DCIs even when multiple consecutive transmissions are missed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed 2-bit DAI field is used in DCI messages, then the system maintains simplicity and low overhead, but the miss detection reliability deteriorates when more than 2 DCI messages are missed
Solution Approach 1:
The patent applies dynamics by making the DAI field bitwidth variable rather than fixed. The base station dynamically selects the DAI bitwidth (2 bits or 3 bits) for each DCI message based on the scheduling scenario, specifically whether multi-PDSCH scheduling is configured. This allows the system to adapt the DAI field size to the actual scheduling needs, improving miss detection reliability when necessary while maintaining simplicity in normal operations.
Solution Approach 2:
The patent changes the parameter of DAI bitwidth from a fixed value to a variable parameter. By modifying the bitwidth parameter based on the multi-PDSCH scheduling configuration, the system can provide enhanced miss detection capability (3 bits) when multiple DCI messages may be missed, while using the standard 2-bit format when only single DCI loss is expected, thus resolving the contradiction between reliability and complexity.
2Measurement precision
If variable bitwidth DAI is used based on multi-PDSCH format, then miss detection accuracy improves, but the processing complexity increases
Solution Approach 1:
The patent applies preliminary action by having the base station and UE pre-configure whether multi-PDSCH scheduling is enabled before actual data transmission. This preliminary configuration allows both sides to know in advance which DAI bitwidth to expect and process, eliminating the need for complex real-time analysis of DCI formats during scheduling. The UE can prepare appropriate reception and processing logic beforehand, reducing actual processing complexity while maintaining high detection accuracy.
3Reliability
If 3-bit DAI is used for all DCI messages, then all missed DCI can be detected, but the overhead increases for every transmission
Solution Approach 1:
The patent applies local quality by applying different DAI bitwidths to different DCI messages based on local scheduling conditions. Instead of uniformly using 3-bit DAI for all DCI messages, the system uses 3-bit DAI only for DCI messages in scenarios where multi-PDSCH scheduling is configured and multiple DCI losses are possible. For other DCI messages where single DCI loss is the concern, the standard 2-bit DAI is used, thus reducing overall overhead while maintaining reliability where needed.
Data Source
AI summary
A base station may transmit downlink control information messages (DCIs) that schedule multiple physical downlink shared channels (PDSCHs) in a single DCI (multi-PDSCH DCIs) to a UE. The base station may generate DCIs with multiple downlink association index (DAI) bitwidths. The base station generate a given DCI with a DAI bitwidth based on a DCI format of the DCI, based on whether the DCI is a multi-PDSCH DCI, based on a carrier that the DCI is transmitted on, or whether the base station is capable of scheduling the UE with multi-PDSCH DCIs in general. The UE may determine the DAI bitwidth of received DCIs and may determine whether any DCIs were missed based on the DAI and the bitwidth of the DAI.