PUSCH Transmission Timing Alignment in TDD Systems
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Solution Overview
Problem
In time division duplex (TDD) mode, the resource scheduling granularity of a physical uplink shared channel (PUSCH) is a resource block (RB), leading to low transmit power and poor data transmission quality due to mismatched time domain locations of subframes, resulting in resource waste.
Innovation Solution
A method where a terminal receives a machine physical downlink control channel (MPDCCH) with timing indication information to determine the time domain location of subframes, aligning the start subframe of PUSCH with the target resource unit, allowing for efficient use of subframes and reducing the number of subcarriers, thereby improving data transmission quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If resource scheduling granularity is set to resource block (RB) in TDD mode, then transmit power on each carrier is relatively low, but resource allocation flexibility is improved
Solution Approach 1:
The patent segments the resource allocation into two levels: resource units (RUs) for time-domain grouping of subframes, and resource blocks (RBs) for frequency-domain allocation within each RU. This hierarchical segmentation allows the system to allocate resources in larger time blocks (improving power efficiency) while maintaining fine-grained frequency allocation (preserving flexibility).
Solution Approach 2:
The patent introduces a new time-domain dimension (resource units spanning multiple subframes) alongside the existing frequency-domain resource blocks. This dimensional extension allows simultaneous optimization of both transmit power (through time-domain aggregation) and allocation flexibility (through frequency-domain granularity).
2Power
If resource unit occupies multiple subframes in time domain, then transmit power per subcarrier increases, but time domain alignment between PUSCH and resource unit becomes complex
Solution Approach 1:
The patent pre-configures mapping relationships between resource units and resource blocks before actual data transmission. By establishing these time-domain alignment rules in advance (rather than dynamically calculating them), the system achieves high transmit power through multi-subframe RUs while avoiding real-time alignment complexity.
Solution Approach 2:
The patent changes the timing parameters by introducing a time offset between the start of the resource unit and the start of the PUSCH transmission. This parameter adjustment allows the PUSCH to be aligned with the resource unit boundary, simplifying time-domain synchronization while maintaining the power benefits of multi-subframe allocation.
3Adaptability or versatility
If PUSCH starts at different time domain location than resource unit, then scheduling flexibility is improved, but data transmission quality deteriorates
Solution Approach 1:
The patent applies different quality requirements to different parts of the resource allocation: at the resource unit level (time domain), flexible scheduling is maintained with variable offsets; however, at the PUSCH transmission level, strict alignment with the resource unit boundary is enforced to ensure high transmission quality. This local differentiation resolves the contradiction between flexibility and reliability.
Data Source
AI summary
A method includes: receiving, by a terminal, a MPDCCH, where the MPDCCH includes a quantity of repeated sending times of the MPDCCH and timing indication information; determining a time domain location of a first subframe based on the quantity of repeated sending times of the MPDCCH, where the first subframe is the last subframe that carries the MPDCCH; determining a time domain location of a second subframe based on the timing indication information and the time domain location of the first subframe, where the second subframe is a start subframe that carries a PUSCH corresponding to the MPDCCH, a resource allocation granularity of the PUSCH corresponding to the MPDCCH is a target resource unit, and a quantity of subcarriers occupied by the target resource unit in frequency domain is less than or equal to 12; and sending, in the second subframe, the PUSCH corresponding to the MPDCCH.