Short TTI Control Channel Search Space Separation
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Solution Overview
Problem
Current 3GPP LTE/LTE-Advanced systems lack specific procedures for search space configuration and blind decoding of short physical downlink control channels (sPDCCH) and legacy PDCCH, as well as efficient transmission and reception schemes for uplink control and data channels in short TTI-based frame structures, leading to challenges in latency reduction and channel overlap issues.
Innovation Solution
A method is provided for detecting downlink control information in short TTI frames by separating aggregation levels for search space configuration and blind decoding, allowing simultaneous transmission of uplink data and sounding reference signals, and configuring uplink channels to overcome symbol duration overlaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If aggregation levels for sPDCCH and legacy PDCCH are not separated, then blind decoding complexity increases, but search space configuration becomes simpler
Solution Approach 1:
The patent segments the aggregation level space by assigning specific aggregation levels (e.g., L=1, L=2) exclusively to sPDCCH and other aggregation levels (e.g., L=4, L=8) exclusively to legacy PDCCH. This segmentation prevents the UE from having to blindly decode both types of channels across all aggregation levels, thereby reducing blind decoding complexity while maintaining clear search space configuration rules for each channel type
2Productivity
If uplink data channel and sounding reference signal are transmitted simultaneously without separation, then uplink transmission efficiency improves, but channel overlap issues occur
Solution Approach 1:
The patent resolves the channel overlap issue by separating uplink data channel and sounding reference signal transmissions in the frequency domain. Specifically, when they would overlap in time and frequency resources, the sounding reference signal is shifted to adjacent subcarriers or resource blocks, allowing simultaneous transmission without interference while maintaining uplink transmission efficiency
3Loss of time
If short TTI frame structure is implemented without specific procedures, then latency is reduced, but control information transmission and reception becomes unreliable
Solution Approach 1:
The patent establishes specific procedures for sPDCCH search space configuration, blind decoding, and uplink channel transmission before actual short TTI operations begin. These predefined procedures ensure that control information transmission and reception follow standardized rules, making short TTI implementation reliable while maintaining low latency
Data Source
AI summary
Provided are a method for transmitting and receiving control information and data between a user equipment and a base station in a short TTI frame structure. In the method, a search space of a legacy PDCCH and a search space of a sPDCCH may be separated from each other on the basis of the type of the search space or aggregation level, etc., and information on the separated search space may be signaled to the user equipment, thereby enabling the user equipment to detect a DCI while reducing the complexity of a blind decoding.