MTC PUSCH Timing Determination for Coverage Extension
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Solution Overview
Problem
Machine-type communication (MTC) apparatuses in coverage extension regions face difficulties in receiving physical downlink control channels (PDCCH) and physical downlink shared channels (PDSCH) due to extended cell coverage, leading to challenges in decoding and transmission timing issues for ACK/NACK and PUSCH.
Innovation Solution
The base station repeatedly transmits bundles of PDCCH and PDSCH on multiple subframes, and the MTC apparatus determines the completion of reception based on a Time Division Duplex (TDD) uplink/downlink configuration, adjusting transmission timings for PUCCH and PUSCH accordingly to ensure successful decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the BS transmits channels to MTC apparatuses in coverage extension regions using normal transmission methods, then the transmission structure remains simple, but the MTC apparatuses have difficulty receiving and decoding the channels
Solution Approach 1:
The transmission of control channels and data channels is segmented across multiple subframes. The BS transmits PDCCHs and PDSCHs in a bundled manner over multiple subframes, allowing MTC apparatuses to accumulate and decode signals incrementally, thereby improving reception reliability without requiring fundamentally new transmission structures
Solution Approach 2:
The patent implements periodic repetition of control channel and data channel transmissions across multiple subframes. This periodic action allows MTC apparatuses in coverage extension regions to receive and decode channels through cumulative processing, resolving the contradiction between reliable reception and transmission structure simplicity
2Reliability
If the BS repeatedly transmits PDCCHs or PDSCHs on multiple subframes to improve decoding performance, then the decoding reliability improves, but the transmission timing for PUCCH/PUSCH becomes complex
Solution Approach 1:
The MTC apparatus autonomously determines the timing for PUCCH/PUSCH transmission based on the bundled subframe structure. The apparatus identifies the last subframe containing PDCCH/PDSCH transmissions and calculates uplink timing accordingly, eliminating the need for complex external timing coordination while maintaining decoding reliability
Solution Approach 2:
The patent establishes a feedback mechanism where the MTC apparatus provides ACK/NACK responses on PUCCH or PUSCH based on the decoded bundled transmissions. The timing of this feedback is systematically determined relative to the bundled subframes, resolving the timing complexity while preserving decoding reliability
3Area of stationary object
If the cell coverage is extended to serve more MTC apparatuses, then the service area increases, but the signal strength at the edge of coverage becomes insufficient for reliable reception
Solution Approach 1:
The patent merges multiple transmissions of the same control channel and data channel across several subframes into a bundled transmission structure. This combining approach allows MTC apparatuses at the coverage edge to accumulate signal energy and improve reception reliability, thereby extending the effective coverage area without sacrificing signal quality
Data Source
AI summary
A method for operating a wireless device, includes receiving downlink control information (DCI), which is repeated on a plurality of downlink subframes determining a last subframe n on which the repetition of the DCI is completed; determining a start subframe n+k to repeatedly transmit a physical uplink shared channel (PUSCH), wherein based on that the last subframe n is unavailable to determine the start subframe n+k to repeatedly transmit the PUSCH, a first subframe among a plurality of subframes after the last subframe n is used as the last subframe n to determine the start subframe n+k; and transmitting the PUSCH repeated over a plurality of subframes starting from the determined start subframe n+k.