EPDCCH Bundle Reception for MTC Devices in Extended Coverage
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Solution Overview
Problem
Machine-type communication (MTC) devices in extended cell coverage regions face difficulties in receiving physical downlink control channels (PDCCH) and enhanced PDCCH (EPDCCH) due to low performance and cost constraints, leading to challenges in decoding these channels effectively.
Innovation Solution
The method involves determining specific search spaces for receiving EPDCCH in MTC devices located in coverage extension regions, based on the number of EPDCCH candidates and different cases classified by DCI format and cyclic prefix usage, allowing for improved decoding performance by repeating channel bundles across multiple subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the BS transmits PDCCH/EPDCCH to MTC devices in coverage extension regions using normal transmission methods, then the transmission can be simple and cost-effective, but the MTC devices have difficulty receiving and decoding the channels due to low performance
Solution Approach 1:
The patent combines multiple EPDCCH transmissions across N subframes into a single bundled transmission unit. The UE receives and decodes the bundled EPDCCH by combining signals from multiple subframes, which improves reception reliability for MTC devices in coverage extension regions without requiring individual high-performance devices for each subframe
Solution Approach 2:
The patent implements periodic repetition of EPDCCH transmissions across N subframes with regular intervals. This periodic transmission pattern allows MTC devices to accumulate signal energy over time through combining, improving decoding reliability while maintaining simple device architecture
2Area of stationary object
If the BS extends cell coverage for MTC devices, then the service area increases, but the MTC devices located in the coverage extension region have difficulty receiving channels transmitted using normal UE methods
Solution Approach 1:
The patent merges EPDCCH transmissions from multiple subframes into a bundled structure that MTC devices can decode by combining signals. This combining approach compensates for the reduced signal strength experienced in coverage extension regions, enabling reliable reception across expanded service areas
Solution Approach 2:
The patent prepares bundled EPDCCH transmissions in advance across N subframes with predetermined configurations. The UE is configured with search space parameters and EPDCCH candidate numbers before receiving the actual transmissions, allowing the devices to efficiently process extended coverage signals without real-time complexity
3Ease of manufacture
If MTC devices are supplied at low price with low performance, then the cost decreases and more devices can be supplied, but the devices have difficulty receiving PDCCH/EPDCCH/PDSCH in coverage extension regions
Solution Approach 1:
The patent employs EPDCCH bundling where low-performance MTC devices combine signals from multiple subframes to achieve reliable decoding. This approach allows the use of simple, cost-effective device hardware while compensating for performance limitations through the bundled transmission structure that provides signal diversity and combining opportunities
Solution Approach 2:
The patent uses periodic EPDCCH transmissions across multiple subframes that allow low-performance devices to accumulate sufficient signal energy through time-domain combining. The regular periodic pattern enables simple device designs to reliably receive signals by integrating over multiple transmission instances rather than requiring high instantaneous processing capability
Data Source
AI summary
One disclosure of the present specification provides a method for receiving EPDCCH by an MTC device. The method comprises: a step for determining a first search space and a second search space for receiving EPDCCH on a first subframe and a second subframe, respectively, from among N-number of subframes, if a bundle of EPDCCHs in which the same EPDCCH is repeated on the N-number of subframes should be received, wherein each of the first and second search spaces is determined on the basis of the number of EPDCCH candidates, and determined by any one of a first case, a second case and a third case classified on the basis of a DCI format and whether a CP being used is a normal CP or an extended CP; and a step for decoding the EPDCCH in the second search space if the cases for determining the first search space and the second search space are the same.