HARQ Processes for Special Subframe PUSCH Transmissions
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Solution Overview
Problem
Current LTE systems face inefficiencies in hybrid automatic repeat request (HARQ) processes for physical uplink shared channel transmissions in special subframes, particularly due to varying resource elements and non-adaptive synchronous HARQ operations, which result in suboptimal coding rates and resource utilization.
Innovation Solution
The introduction of new HARQ processes with a fixed Round Trip Time (RTT) of 10 ms for Uplink Pilot Time Slot (UpPTS) PUSCH transmissions, along with PHICH resource reservation and multi-subframe scheduling, allows for efficient scheduling and retransmissions in special subframes, maintaining backward compatibility and enhancing UL peak spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If non-adaptive synchronous HARQ operations are used in special subframes, then implementation simplicity is maintained, but resource utilization and coding rates become suboptimal
Solution Approach 1:
The patent introduces dynamic HARQ processes that can adapt to special subframe configurations. Instead of fixed synchronous HARQ operations, the system dynamically determines HARQ timing and resource allocation based on the specific special subframe structure (DwPTS, GP, UpPTS lengths), enabling optimal resource utilization while maintaining manageable complexity through structured adaptation rules.
Solution Approach 2:
The patent changes key HARQ parameters including Round Trip Time (RTT) and timing relationships to match special subframe characteristics. By adjusting HARQ RTT to 10 ms and modifying the timing between PUSCH transmission and PHICH reception according to special subframe configurations, the system achieves both improved resource utilization and maintained operational simplicity through parameter standardization.
2Adaptability or versatility
If varying resource elements are used in special subframes, then flexibility in transmission is improved, but coding rates become suboptimal
Solution Approach 1:
The patent standardizes the HARQ Round Trip Time parameter to 10 ms for special subframes, providing a fixed reference point that enables optimal coding rate calculation. This parameter change allows the system to maintain transmission flexibility through configurable resource elements while achieving consistent, optimal coding rates through standardized timing parameters.
Solution Approach 2:
The patent establishes predetermined HARQ timing relationships and resource allocation patterns for special subframes before actual transmission occurs. By pre-defining the 10 ms RTT and associated timing relationships, the system prepares optimal coding parameters in advance, enabling both flexible resource element usage and consistent optimal coding rates during transmission.
3Productivity
If PHICH resource reservation is implemented for UpPTS PUSCH transmissions, then retransmission efficiency is improved, but resource allocation complexity increases
Solution Approach 1:
The patent reserves PHICH resources in advance for UpPTS PUSCH retransmissions, establishing predetermined resource locations before transmission occurs. This preliminary resource allocation improves retransmission efficiency by eliminating resource allocation delays while maintaining manageable complexity through standardized reservation patterns and timing relationships.
Solution Approach 2:
The system implements self-service resource allocation for HARQ retransmissions by automatically determining PHICH resource locations based on pre-established timing relationships and resource mapping rules. This self-service mechanism improves retransmission efficiency through rapid resource determination while keeping allocation complexity manageable through automated, rule-based resource assignment.
4Productivity
If multi-subframe scheduling is used in special subframes, then spectral efficiency is improved, but scheduling complexity increases
Solution Approach 1:
The patent implements dynamic multi-subframe scheduling that adapts to special subframe configurations while maintaining structured scheduling rules. By dynamically adjusting scheduling parameters based on special subframe characteristics (DwPTS length, UpPTS position) while following standardized procedures, the system achieves improved spectral efficiency without excessive scheduling complexity.
Solution Approach 2:
The patent standardizes key scheduling parameters including HARQ RTT (10 ms) and timing relationships for special subframes. These parameter standardizations enable efficient multi-subframe scheduling by providing consistent reference points that simplify scheduling decisions while maximizing spectral efficiency through optimized resource utilization across multiple subframes.
Data Source
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AI summary
A method and apparatus may include receiving an uplink grant in a specific subframe of a frame and/or a physical hybrid-ARQ indicator channel transmission, for a physical-uplink-shared-channel transmission or retransmission on a special subframe. The method may also include determining that the uplink grant validates transmitting a physical-uplink-shared-channel transmission on the special subframe, or that the physical hybrid-ARQ indicator channel transmission validates transmitting a physical-uplink-shared-channel retransmission on the special subframe. The method may also include determining transmission parameters for transmitting the physical-uplink-shared-channel transmission or retransmission. The method may also include transmitting the physical-uplink-shared-channel transmission or retransmission on the special subframe.