ePDCCH Aggregation Level Switching for Control Channel Adaptability
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Solution Overview
Problem
In LTE-Advanced systems, the existing methods for switching between transmission methods for ePDCCH (Enhanced Physical Downlink Control Channel) face challenges such as increased blind decoding times and signaling requirements, which can lead to control delays and inefficiencies in resource allocation, particularly in CoMP (coordinated multiple point transmission and reception) operations and interference control.
Innovation Solution
A method that allows switching between single antenna port transmission and transmission diversity using multiple antenna ports by configuring aggregation levels for ePDCCH candidates, where blind decoding is performed using one of these methods based on the aggregation level, reducing the need for increased blind decoding times and signaling requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transmission method switching is implemented using existing methods (higher layer signaling or per-candidate indication), then transmission method adaptability is improved, but signaling overhead and blind decoding complexity increase
Solution Approach 1:
The patent applies local quality by configuring different aggregation levels for different ePDCCH candidates based on their specific characteristics. Each candidate can have a tailored aggregation level (1, 2, 4, or 8 RB pairs) matched to its required reliability and channel conditions, rather than applying a uniform transmission method across all candidates. This localized configuration enables transmission method adaptability while avoiding the need for extensive signaling overhead.
Solution Approach 2:
The patent implements dynamics by enabling the receiver to dynamically select appropriate transmission methods (single antenna port or transmission diversity) based on the aggregation level of each ePDCCH candidate. The system can adapt transmission methods in real-time according to channel conditions and candidate priorities, with higher aggregation levels potentially using more robust transmission diversity methods while lower aggregation levels use simpler single antenna port methods.
2Adaptability or versatility
If blind decoding is performed for multiple mapping candidates with different transmission methods, then transmission method flexibility is improved, but processing time and complexity increase
Solution Approach 1:
The patent segments the blind decoding process by dividing ePDCCH candidates into different groups based on their aggregation levels. The receiver performs blind decoding separately for each aggregation level group, applying appropriate transmission methods to each segment. This segmentation reduces the overall complexity by avoiding exhaustive blind decoding across all candidates with all possible transmission methods, as each segment only requires decoding with its specific configured aggregation level.
Solution Approach 2:
The patent applies partial action by having the receiver perform blind decoding only with the aggregation levels that are actually configured for each candidate, rather than attempting all possible aggregation levels (1, 2, 4, 8) for every candidate. This partial approach reduces processing time and complexity while maintaining the necessary transmission method flexibility for configured candidates.
3Manufacturing precision
If aggregation levels are configured for each ePDCCH candidate, then resource allocation precision is improved, but control signal overhead increases
Solution Approach 1:
The patent applies universality by using the aggregation level configuration to serve multiple functions simultaneously: it determines both the resource allocation size (number of RB pairs) and implicitly indicates the appropriate transmission method to use. This multi-functionality eliminates the need for separate signaling elements to specify transmission methods, as the aggregation level itself carries dual meaning for both resource allocation and transmission method selection.
Solution Approach 2:
The patent uses parameter changes by varying the aggregation level parameter (with four possible values: 1, 2, 4, or 8 RB pairs) to encode different transmission method requirements. By changing this single parameter, the system simultaneously controls resource allocation precision and transmission method selection, reducing control signal overhead compared to using separate parameters for each function.
Data Source
AI summary
A communication apparatus includes circuitry and a transmitter. The circuitry maps a precoded downlink control signal to one of a plurality of mapping candidates. The precoded downlink control signal is prepared using a first precoding for single-antenna port transmission with a single antenna port in localized allocation mode. The precoded downlink control signal is prepared using a second precoding for multi-antenna ports transmission with two antenna ports in distributed allocation mode. The plurality of mapping candidates is comprised of a plurality of aggregation levels, and one or more of the aggregation levels that is higher than a boundary among the plurality of aggregation levels is associated with only the multi-antenna ports transmission, the boundary being determined based on signaling indicated from the base station apparatus. The transmitter transmits the precoded downlink control signal.