Contention-Based PUSCH Transmission Result Determination
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Solution Overview
Problem
In wireless communication systems, particularly in LTE, determining the result of transmission for contention-based PUSCH is challenging due to the lack of immediate ACK indication from the eNB, leading to uncertainty in successful data transmission and potential collisions, which affects latency and throughput.
Innovation Solution
The User Equipment (UE) employs a timer-based mechanism to determine the success of transmission on contention-based grants by monitoring ACK indications from the eNB, retransmitting data if no ACK is received within the timer expiry, and utilizing unique identifiers in MAC PDUs to differentiate between UEs sharing resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If contention-based PUSCH transmission is used to allow synchronized UEs to transmit without scheduling requests, then latency is reduced and productivity is improved, but transmission reliability deteriorates due to lack of immediate ACK indication and potential collisions
Solution Approach 1:
The patent applies preliminary action by pre-configuring UEs with contention-based PUSCH resources and unique identifiers before transmission. UEs are prepared with their specific time-frequency resources and identifier information in advance, allowing them to transmit immediately without scheduling requests, thus reducing latency while maintaining reliability through pre-planned resource allocation
Solution Approach 2:
The patent implements feedback mechanism where the eNB monitors PUSCH transmissions from multiple UEs and provides ACK/NACK indications. The eNB detects collisions by comparing received signals with expected transmissions and feeds back collision information to UEs, enabling them to adjust future transmissions and improving overall transmission reliability in the contention-based access scheme
2Productivity
If multiple UEs share the same contention-based resources to improve productivity, then resource utilization is improved, but collision risk increases leading to worsened transmission reliability
Solution Approach 1:
The patent applies segmentation by dividing contention-based resources into multiple segments, including different time-frequency resources and unique identifier spaces. Each UE is assigned a specific segment (combination of time-frequency resource and identifier), allowing multiple UEs to share overall resources while maintaining individual distinguishability, thus enabling high resource utilization with reduced collision impact
Solution Approach 2:
The patent uses unique identifiers as intermediaries between multiple UEs sharing contention resources. These identifiers are embedded in PUSCH transmissions and serve as mediators that allow the eNB to distinguish between different UEs' transmissions even when they share the same physical resources, enabling reliable collision detection and feedback without reducing resource sharing efficiency
3Ease of operation
If a timer-based mechanism is used to determine transmission success, then device complexity is reduced and ease of operation is improved, but transmission reliability worsens due to uncertainty before timer expiry
Solution Approach 1:
The patent applies self-service by implementing a timer-based mechanism where each UE autonomously manages its own transmission status determination. The UE starts a timer after PUSCH transmission and automatically determines success or failure based on whether the timer expires before receiving eNB feedback, without requiring complex external control or intervention, thus improving ease of operation while maintaining acceptable reliability through standardized timer management
Data Source
AI summary
The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for determining result of transmission for contention-based PUSCH in a wireless communication system, the method comprising: transmitting a MAC PDU using a CB grant to an eNB; starting a timer when the UE transmits the MAC PDU using the CB grant; monitoring an ACK indication transmitted by the eNB while the timer is running; considering that the MAC PDU transmission using the CB grant is failed if the UE doesn't receive the ACK indication from the eNB until the timer expires; and retransmitting the MAC PDU to the eNB.