EPDCCH Search Space Design for MTC Power Reduction
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Solution Overview
Problem
Existing 3GPP LTE systems incur high power consumption during blind decoding of EPDCCH candidates, which is undesirable for MTC UEs requiring low power consumption and often experience poor channel quality, leading to inefficient DCI detection.
Innovation Solution
The proposed EPDCCH search space design extends into the time domain by defining search spaces across multiple subframes rather than multiple ECCEs in one subframe, allowing for reduced power consumption and improved detection performance by signaling the number of subframes and search units within an occasion period, enabling more efficient DCI transmission and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blind decoding is performed on all possible EPDCCH candidates in each subframe, then DCI detection coverage is improved, but power consumption increases significantly
Solution Approach 1:
The patent segments the EPDCCH search space across multiple subframes instead of confining it to a single subframe. By distributing ECCE candidates across multiple subframes and introducing a subframe offset parameter, the system divides the blind decoding workload temporally, allowing UEs to detect DCI with reduced power consumption while maintaining detection coverage.
Solution Approach 2:
The patent implements periodic EPDCCH transmission and detection by defining search spaces that span multiple subframes with specific periodicity. The subframe offset and occasion period parameters enable periodic action patterns, where DCI transmission occurs at predetermined intervals, allowing UEs to enter low-power states between detection occasions.
2Speed
If EPDCCH search space is confined to multiple ECCEs in one subframe, then detection speed is improved, but power consumption increases for MTC UEs
Solution Approach 1:
The patent transitions the EPDCCH search space from a spatial-only dimension (multiple ECCEs within one subframe) to a temporal dimension by spanning multiple subframes. This dimensional change allows the system to maintain detection capability while reducing the concentration of blind decoding operations in a single subframe, thereby reducing power consumption for MTC UEs.
3Use of energy by moving object
If search space is extended across multiple subframes, then power consumption is reduced, but detection complexity increases
Solution Approach 1:
The patent introduces specific parameters (subframe offset, occasion period, number of subframes) to control and standardize the multi-subframe search space structure. These parameter changes provide a systematic framework that manages detection complexity by defining clear rules for UE behavior, rather than allowing arbitrary complex patterns.
Data Source
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AI summary
Embodiments of the present invention generally relate to enhanced physical downlink control channel (EPDCCH) search space determination. In one embodiment, a base station may identify an index of the current EPDCCH occasion period, each EPDCCH occasion period including a number of subframes, and the subframes being divided to a number of search units. A distribution of EPDCCH candidates corresponding to at least one EPDCCH aggregation level in the EPDCCH occasion period may be determined based on the index of the EPDCCH occasion period and the number of search units in the EPDCCH occasion period. The base station may then select, from the distribution of the EPDCCH candidates, an EPDCCH candidate for transmitting downlink control information (DCI) to a UE.