PDSCH RE Mapping for MTC Coverage Extension
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Solution Overview
Problem
Machine type communication (MTC) devices in extended cell coverage areas face difficulties in receiving physical downlink shared channels (PDSCH) and physical downlink control channels (PDCCH) due to inaccurate scheduling information and varying resource element (RE) locations, leading to decoding challenges.
Innovation Solution
Implementing a method where a base station repeatedly transmits PDSCH and PDCCH across multiple subframes, mapping PDSCH to specific REs in each subframe and performing rate-matching and puncturing to ensure consistent decoding, allowing MTC devices to combine signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the base station transmits PDSCH to MTC apparatus in coverage extension region as if transmitting to normal UE, then the transmission method is simple, but the MTC apparatus has difficulty in receiving the PDSCH
Solution Approach 1:
The patent segments the PDSCH transmission into multiple subframes (first subframe, second subframe, third subframe) with different RE mapping strategies. In the first subframe, PDSCH is mapped to REs excluding those used for PDCCH and reference signals. In subsequent subframes, PDSCH is mapped to REs including those used for PDCCH and reference signals in the first subframe. This segmentation allows the MTC apparatus to receive and combine PDSCH signals across multiple subframes, improving reception reliability in coverage extension regions.
2Productivity
If the base station transmits bundle of PDSCHs starting from the same subframe, then the transmission efficiency is high, but the MTC device cannot decode the PDSCH accurately due to varying RE locations
Solution Approach 1:
The patent applies preliminary action by first mapping PDSCH to specific REs in the first subframe (excluding PDCCH and reference signal REs), then using this mapping information to guide the RE mapping in subsequent subframes. The base station transmits PDSCH in the first subframe with a defined RE mapping, then in subsequent subframes maps PDSCH to REs that include the PDCCH and reference signal REs from the first subframe. This preliminary mapping establishes a reference for the MTC apparatus to accurately combine signals across subframes.
Solution Approach 2:
The patent implements dynamic RE mapping for PDSCH across multiple subframes. The RE locations for PDSCH change dynamically between subframes based on a predetermined pattern. In the first subframe, PDSCH uses REs excluding PDCCH and reference signals. In subsequent subframes, PDSCH uses REs that include PDCCH and reference signal locations from the first subframe. This dynamic mapping allows the MTC apparatus to receive signals in different locations and combine them effectively through signal processing.
3Adaptability or versatility
If the base station extends cell coverage for MTC apparatus, then more MTC apparatuses can be served, but the MTC apparatus has difficulty in receiving channels due to signal degradation
Solution Approach 1:
The patent merges multiple PDSCH transmissions across different subframes into a single logical data stream. The base station transmits PDSCH in the first subframe, then transmits PDSCH in subsequent subframes with overlapping RE mappings. The MTC apparatus receives all these transmissions and combines them through signal processing (such as combiner filtering and signal accumulation) to reconstruct the complete data signal. This merging of multiple transmissions compensates for signal degradation in coverage extension regions.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining PDSCH transmission across multiple subframes with consistent data content. The base station repeatedly transmits the same PDSCH data in the first subframe, second subframe, and third subframe, with each transmission containing useful signal components. The MTC apparatus continuously receives and accumulates these transmissions, ensuring that the useful signal action continues uninterrupted across time, thereby improving reception reliability in extended coverage areas.
Data Source
AI summary
One embodiment of the present specification provides a method for transmitting, to a machine type communication (MTC) device, a physical downlink shared channel (PDSCH) including downlink data. The method can comprise the steps of: mapping the PDSCH on a resource element (RE) of a first subframe among a plurality of subframes and transmitting the same, when a base station performs PDSCH bundle transmission for repeatedly transmitting the same PDSCH to the MTC device on the plurality of subframes; and mapping, by the base station, the PDSCH on an RE of a second subframe among the plurality of subframes with respect to the RE of the first subframe, on which the PDSCH is mapped, to enable the MTC device to decode a bundle of the PDSCHs through the combination of RE units, and transmitting the same.