Rate Matching for Broadcast Channels in mmW NR
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Solution Overview
Problem
In wireless communication systems, especially in millimeter wave (mmW) New Radio (NR) systems, user equipment (UE) faces challenges in receiving broadcast information via physical downlink shared channels (PDSCH) when outside of an RRC connected state, due to uncertainty about the appropriate resources for monitoring, leading to difficulties in decoding broadcast information like RMSI and OSI.
Innovation Solution
The system provides an indication to the UE of the length of the PDSCH in terms of downlink symbols, allowing the UE to monitor and decode the broadcast information efficiently, even when outside of an RRC connected state, by transmitting this information through a DCI on a physical downlink control channel, and enabling blind decoding over multiple sets of downlink symbols with varying lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs blind decoding over multiple sets of downlink symbols with varying lengths, then the capability to receive and decode broadcast information is improved, but the complexity of the decoding process increases
Solution Approach 1:
The base station provides advance indication of the PDSCH length in terms of downlink symbols through DCI signaling before the actual transmission. This preliminary information allows the UE to configure its blind decoding process with the correct expected length, eliminating the need to test multiple hypothesis and significantly reducing decoding complexity while maintaining reliability.
2Ease of operation
If the UE monitors broadcast channels without RRC connected state, then accessibility to broadcast information is improved, but the uncertainty about appropriate monitoring resources increases
Solution Approach 1:
The patent introduces DCI (Downlink Control Information) as an intermediary mechanism that carries indication information about the PDSCH length. This intermediary signaling element bridges the gap between the base station's transmission configuration and the UE's monitoring requirements, enabling the UE to accurately identify monitoring resources even when not in RRC connected state.
3Adaptability or versatility
If the base station transmits PDSCH with variable length, then flexibility in broadcast information transmission is improved, but the latency in receiving and decoding the information increases
Solution Approach 1:
The base station provides feedback information about the actual PDSCH length used in the transmission through DCI signaling. This feedback mechanism allows the UE to quickly identify the correct decoding parameters without having to exhaustively search through multiple possible lengths, thereby reducing decoding latency while maintaining transmission flexibility.
Data Source
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Figure 3A~3D
AI summary
Methods, systems, and devices for wireless communications are described. A method may include receiving, from a base station and while being outside of a radio resource control (RRC) connected state, an indication of a length of downlink symbols used to transmit a physical downlink shared channel (PDSCH) that carries broadcast information, and decoding the PDSCH based on the indication. Another method may include receiving, from a base station, a PDSCH that carries broadcast information over a plurality of downlink symbols and while being outside of an RRC connected state, perform a first blind decoding of the PDSCH over a first set of the plurality of downlink symbols, and perform a second blind decoding of the PDSCH during a second set of the plurality of downlink symbols, the second set being different in length than the first set.