PUCCH Interference Mitigation via PUSCH Feedback Annexation
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Solution Overview
Problem
In LTE systems, excessive interference on the PUCCH can lead to unsuccessful receipt of ACKs by the eNodeB, resulting in unnecessary downlink retransmissions, which reduces effective throughput for both the affected UE and other UEs sharing air-link resources.
Innovation Solution
A method where a UE determines if the PUCCH is compromised by assessing the number of retransmitted downlink transport blocks and current channel conditions, then switches to transmitting uplink-feedback data via the PUSCH by sending a scheduling-request message, accessing pseudo uplink data, and annexing uplink-feedback data to it, thereby avoiding PUCCH interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a UE transmits uplink-feedback data via the PUCCH, then the feedback can be sent efficiently, but excessive interference on the PUCCH causes unsuccessful receipt of ACKs by the eNodeB, resulting in unnecessary downlink retransmissions
Solution Approach 1:
The patent introduces the PUSCH as an intermediary channel to replace the PUCCH when interference is detected. The UE switches from using the direct PUCCH channel to using the PUSCH channel as a mediator for transmitting uplink-feedback data, thereby avoiding the interfered PUCCH channel and ensuring reliable ACK receipt.
Solution Approach 2:
The patent changes the transmission parameter by switching the channel type from PUCCH to PUSCH based on interference conditions. The UE monitors PUCCH interference levels and dynamically changes the transmission channel parameter, selecting PUSCH when PUCCH interference exceeds a threshold, thus maintaining reliable feedback transmission.
2Reliability
If the eNodeB receives unsuccessful ACKs due to PUCCH interference, then the system maintains protocol compliance, but unnecessary downlink retransmissions occur, reducing effective throughput
Solution Approach 1:
The patent implements a feedback mechanism where the UE monitors the success of ACK transmission and provides feedback about PUCCH interference conditions. Based on this feedback, the UE adjusts its transmission strategy by switching to PUSCH, thereby preventing unnecessary retransmissions and improving throughput while maintaining protocol compliance.
Solution Approach 2:
The patent applies preliminary action by having the UE detect and assess PUCCH interference conditions before transmitting uplink-feedback data. The UE performs preliminary monitoring of interference levels and proactively switches to the PUSCH channel if interference is detected, preventing transmission failures before they occur and avoiding unnecessary retransmissions.
3Reliability
If a UE switches to transmitting via the PUSCH when PUCCH is compromised, then reliable transfer of uplink-feedback data is achieved, but the UE must perform additional actions such as sending scheduling-request messages and accessing pseudo uplink data
Solution Approach 1:
The patent uses the PUSCH as an intermediary channel that handles both data transmission and feedback transmission. By switching to PUSCH, the UE leverages this existing channel's capabilities to carry both pseudo uplink data and uplink-feedback data, thereby achieving reliable feedback transfer without requiring a completely new transmission mechanism.
Solution Approach 2:
The patent exploits the multi-functionality of the PUSCH channel, which can carry both user data and uplink-feedback data. By using PUSCH for feedback transmission, the UE utilizes a channel already designed for data transmission, thereby achieving reliable feedback delivery while avoiding the need for separate dedicated feedback channels and reducing overall system complexity.
Data Source
AI summary
Disclosed herein are embodiments of a method and embodiments of an apparatus for mitigating physical uplink control channel (PUCCH) interference in Long Term Evolution (LTE) systems. In an embodiment, a wireless-communication device receives downlink transport blocks and responsively transmits corresponding acknowledgement messages via the PUCCH. The device determines that an excessive number of unsolicited (i.e., already-acknowledged) retransmitted downlink transport blocks has been received, and responsively: transmits a scheduling-request message via a random access channel (RACH) and obtains a physical uplink shared channel (PUSCH) scheduling grant, accesses pseudo uplink data, annexes uplink-feedback data to the pseudo uplink data, and transmits the pseudo uplink data and annexed uplink-feedback data via the PUSCH in accordance with the obtained PUSCH scheduling grant.