MTC UE PDCCH Monitoring via Time-Domain Search Space Multiplexing
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Solution Overview
Problem
Low-cost MTC UEs with restricted bandwidth face challenges in receiving Physical Downlink Control Channel (PDCCH) signals due to the inability to simultaneously receive common and user-specific downlink control information when these channels are multiplexed beyond the restricted bandwidth, leading to signal delay and potential operational failures.
Innovation Solution
A user apparatus is configured to monitor and receive downlink control information by multiplexing common and user-specific search spaces in a frequency or time direction within a predetermined physical downlink control channel, allowing for efficient blind decoding of signals even under bandwidth restrictions, using a monitoring control unit to manage the reception of these channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bandwidth of the UE is restricted to reduce cost, then the cost of the MTC UE is reduced, but the UE cannot receive PDCCH transmitted by the whole system band
Solution Approach 1:
The patent transitions from frequency-domain multiplexing (PDCCH in system band) to time-domain multiplexing (EPDCCH in restricted bandwidth across multiple subframes). By allowing the UE to monitor EPDCCH in multiple subframes within its restricted bandwidth, the system achieves the same control information delivery without requiring the UE to access the full system band frequency range.
2Adaptability or versatility
If EPDCCH is used for bandwidth-restricted UE, then the UE can receive control information within restricted bandwidth, but the UE cannot receive common DCI transmitted by PDCCH CSS
Solution Approach 1:
The patent merges the functions of PDCCH CSS and EPDCCH by allowing the UE to monitor both common search space (for common DCI) and user-specific search space (for UE-specific DCI) within the EPDCCH structure. This integration ensures that bandwidth-restricted UEs can receive both common and dedicated control information without requiring separate PDCCH resources outside their restricted bandwidth.
3Productivity
If CSS and USS are placed in frequency-separated resources, then blocking probability is reduced and flexibility is improved, but the LC MTC UE cannot receive both CSS and USS simultaneously
Solution Approach 1:
The patent resolves the spatial conflict by introducing time-domain separation. Instead of placing CSS and USS in frequency-separated resources that exceed the UE's bandwidth, the system schedules CSS and USS in different subframes within the UE's restricted bandwidth. This allows the UE to sequentially receive both common and user-specific control information without requiring simultaneous frequency-domain resources.
4Reliability
If CSS and USS are multiplexed within restricted bandwidth, then the UE can receive both search spaces, but capacity and delay of control information increase
Solution Approach 1:
The patent implements periodic monitoring patterns where the UE alternates between monitoring common search space and user-specific search space across different subframes. This periodic structure allows the UE to efficiently receive both types of control information within its restricted bandwidth while minimizing idle monitoring periods, thereby reducing overall delay compared to continuous monitoring of all search spaces simultaneously.
Data Source
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AI summary
A user apparatus configured to perform communication with a base station in a mobile communication system, wherein a common search space and a user specific search space are multiplexed in a predetermined physical downlink control channel transmitted from the base station, the user apparatus including: a monitoring control unit configured to monitor, for each predetermined time frame, any one of the common search space and the user specific search space in the predetermined physical downlink control channel in order to obtain downlink control information.