Data Channel Search Space for Low Latency Wireless
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Solution Overview
Problem
Conventional wireless communication systems face challenges in achieving ultra-reliable, low-latency communications due to bottlenecks in control channel-centric approaches, which struggle with adaptive link conditions and soft combining, particularly in aggressive latency and reliability targets for services like URLLC.
Innovation Solution
The implementation of data channel-based communication methods that utilize a search space for initial and retransmission data transmissions, avoiding control channel signaling and allowing adaptive resource allocation and modulation schemes, enabling blind decoding and soft combining for improved reliability within latency bounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If control channel signaling is used for grant-based communications, then device complexity is reduced, but latency and reliability deteriorate due to bottlenecks
Solution Approach 1:
The patent extracts the scheduling function from the control channel and implements it directly in the data channel. The base station sends scheduling information and data together in the same physical downlink shared channel (PDSCH), eliminating the separate control channel signaling step. This extraction removes the bottleneck that caused latency while keeping device complexity manageable through standardized processing.
Solution Approach 2:
The patent merges the control channel and data channel into a single transmission structure. The grant-based scheduling information and the actual data are combined in the same PDSCH transmission, allowing the wireless device to decode both simultaneously. This merging eliminates the sequential processing delay between control channel reception and data transmission, directly reducing latency.
2Device complexity
If control channel signaling is used for grant-based communications, then device complexity is reduced, but reliability deteriorates due to inability to perform soft combining
Solution Approach 1:
The patent merges control information and data into the same physical channel, enabling the wireless device to apply soft combining techniques. Since both the scheduling grant and data are transmitted in the PDSCH, the device can combine multiple transmissions of the same data packet across different time instances, improving reliability through diversity gain while maintaining manageable complexity.
Solution Approach 2:
The patent implements HARQ feedback mechanisms where the wireless device sends acknowledgment or negative acknowledgment for received data. When a transmission fails, the base station retransmits the data with updated scheduling information in the same channel structure, allowing the device to combine the retransmitted data with previously received versions, thereby improving reliability through feedback-driven error correction.
3Reliability
If adaptive link conditions are supported with control channel signaling, then reliability improves, but latency increases due to additional signaling overhead
Solution Approach 1:
The patent combines link adaptation information (MCS indices, resource allocation) with data transmissions in the same PDSCH. This eliminates the separate control channel signaling required for traditional link adaptation, removing the associated latency overhead while maintaining the ability to adapt to changing channel conditions through embedded scheduling information.
Solution Approach 2:
The patent changes the parameter representation by embedding modulation and coding scheme (MCS) indices directly in the data channel transmission rather than signaling them separately. The base station adjusts MCS parameters adaptively based on channel conditions, and these parameter changes are conveyed within the data transmission itself, enabling fast link adaptation without additional signaling delay.
4Reliability
If data channel-based communication is implemented, then reliability and adaptability improve, but device complexity increases due to blind decoding requirements
Solution Approach 1:
The patent segments the blind decoding process into manageable parts by organizing the search space into specific candidate positions and aggregation levels. The wireless device only needs to decode a limited set of predefined candidates rather than searching the entire frequency-time spectrum, reducing computational complexity while maintaining the reliability benefits of data channel-based communication.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the search space parameters and decoding candidates during initial connection setup. The base station and device agree on the structure of the data channel search space in advance, so the device doesn't need to perform complex real-time analysis. This preliminary configuration reduces runtime processing complexity while enabling reliable blind decoding.
Data Source
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AI summary
Methods, systems, and devices for wireless communication utilizing a data channel search space for initial data transmissions and retransmissions are described. In one aspect, a base station may configure a data channel search space and a plurality of monitoring occasions for a wireless device. The data channel search space may include a plurality of sets of decoding candidates on which the wireless device may receive data transmissions from the base station. At least one of a frequency location, a resource size, or a modulation and coding scheme can vary between different sets of decoding candidates. The wireless device performs blind decoding in its data channel search space to communicate with the base station.