PDCCH Soft Combining Across TTIs for Low-Latency Decoding
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Solution Overview
Problem
Current techniques for transmitting control channels in wireless communication systems, such as PDCCH for URLLC, fail to meet stringent latency and reliability requirements, leading to performance issues.
Innovation Solution
A base station transmits repeated versions of the PDCCH over multiple TTIs, each scrambled with a different scrambling code, and the UE performs soft-combining decoding operations using multiple descrambling codes to enhance performance and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate decoders are used for each control channel to ensure reliable decoding, then decoding reliability is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent combines multiple separate decoders into a single shared decoder that processes control channels sequentially. The shared decoder decodes PDCCH, PDSCH, and PUCCH channels by switching between them using a channel identifier, thereby reducing device complexity and power consumption while maintaining decoding reliability through dedicated processing of each channel type.
Solution Approach 2:
The shared decoder is designed with multi-functionality to handle different control channel types (PDCCH, PDSCH, PUCCH) using a unified decoding architecture. By making the decoder universal and adaptable to multiple channel types through configuration parameters and channel identifiers, the system avoids the need for multiple specialized decoders.
2Reliability
If separate decoders are used for each control channel to ensure reliable decoding, then decoding reliability is improved, but power consumption increases
Solution Approach 1:
The patent combines multiple separate decoders into a single shared decoder that processes control channels sequentially. The shared decoder decodes PDCCH, PDSCH, and PUCCH channels by switching between them using a channel identifier, thereby reducing device complexity and power consumption while maintaining decoding reliability through dedicated processing of each channel type.
Solution Approach 2:
The system employs periodic action by enabling the shared decoder to process different control channels in sequential time slots rather than continuously operating multiple decoders simultaneously. The network device indicates which channel to decode at each time slot through a channel identifier, allowing the decoder to be activated only when needed for specific channel decoding tasks.
3Measurement precision
If channel estimation and interference cancellation are performed before decoding to improve accuracy, then measurement precision is improved, but processing time and complexity increase
Solution Approach 1:
The patent applies preliminary action by performing channel estimation and interference cancellation operations before the actual decoding process. The method estimates channel state information and cancels interference from other channels (such as estimating PDSCH channel to cancel interference in PUCCH decoding) in advance, so that the main decoder can work with pre-processed, higher-quality signals, reducing the need for repeated processing.
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. A wireless device such as a user equipment (UE) may monitor a search space of a control channel for at least one downlink transmission. The UE may perform a plurality of decoding operations on a plurality of decoding candidates associated with the downlink control information format transmitted in a plurality of transmission time intervals (TTIs). In some cases, the plurality of decoding operations may comprise performing a first decoding on a first decoding candidate received in a current TTI, the first decoding operation applying a first descrambling code to the first decoding candidate, and performing a second decoding operation on a combined decoding candidate that comprises soft combined information from the first and second decoding candidate, the second decoding candidate received in a prior TTI.