ACK/NACK Transmission in D2D Wireless Systems
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Solution Overview
Problem
Current wireless communication systems face challenges in transmitting ACK/NACK signals due to half-duplex constraints, which restrict efficient data transmission and reception between user equipments (UEs) with non-complementary Time Resource Patterns (T-RPTs, particularly in direct device-to-device (D2D) communication scenarios.
Innovation Solution
The method involves comparing the T-RPTs of two UEs to determine optimal subframes for transmitting ACK/NACK signals, allowing repeated transmissions in specific subframes where the T-RPT values align, thereby overcoming the half-duplex constraint and ensuring successful data acknowledgment and retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If D2D communication is implemented to reduce network overhead, then network efficiency is improved, but ACK/NACK transmission reliability deteriorates due to half-duplex constraints
Solution Approach 1:
The patent implements periodic ACK/NACK transmissions at predetermined intervals to ensure reliable feedback delivery. The receiving UE transmits ACK/NACK signals periodically in uplink subframes, allowing the transmitting UE to receive multiple feedback opportunities and improving overall transmission reliability despite half-duplex constraints.
Solution Approach 2:
The patent establishes a feedback mechanism where the receiving UE sends ACK/NACK signals to the transmitting UE, and the transmitting UE can send retransmissions based on received feedback. This closed-loop feedback system ensures reliable data transmission by allowing retransmissions when NACK is received or ACK is not received within expected timeframes.
2Productivity
If T-RPT patterns are used for data transmission, then data transmission efficiency is improved, but ACK/NACK transmission conflicts worsen due to non-complementary patterns between UEs
Solution Approach 1:
The patent introduces a coordinating mechanism that acts as an intermediary to resolve T-RPT pattern conflicts. The transmitting and receiving UEs coordinate their T-RPT patterns to ensure they are non-overlapping, with the receiving UE's ACK/NACK transmission subframes selected to avoid conflicts with the transmitting UE's data transmission subframes, thereby eliminating transmission conflicts.
Solution Approach 2:
The patent dynamically adjusts T-RPT pattern parameters (such as pattern indices and subframe allocations) to resolve conflicts. When conflicts are detected, the UEs change their T-RPT parameters to select alternative patterns that are complementary, ensuring that data transmission and ACK/NACK transmission occur in different subframes without interference.
3Reliability
If repeated ACK/NACK transmissions are implemented, then transmission reliability is improved, but time resources are consumed
Solution Approach 1:
The patent implements repeated ACK/NACK transmissions only when necessary, rather than continuously. The receiving UE transmits ACK/NACK repeatedly in multiple uplink subframes, but the transmitting UE stops expecting feedback after a predetermined number of repetitions or when an ACK is successfully received, thereby avoiding excessive time consumption while maintaining reliability.
Solution Approach 2:
The patent establishes predetermined rules and configurations for repeated ACK/NACK transmissions before actual transmission occurs. The UEs are pre-configured with T-RPT patterns, maximum repetition counts, and timing relationships, allowing them to efficiently execute repeated transmissions without requiring complex real-time decisions, thus minimizing time overhead.
Data Source
Figure 1~1(b)
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AI summary
One embodiment of the present invention relates to a method for a second user equipment transmitting a receipt acknowledgement in a wireless communication system, the method for transmitting the receipt acknowledgement comprising the steps of: the second UE receiving data from the first UE; determining a subframe to transmit the receipt acknowledgement by comparing a time resource pattern for transmission (T-RPT) of the first UE and a T-RPT of the second UE; and transmitting the receipt acknowledgement relating to the data from the determined subframe to the first UE.