HARQ Feedback Transmission via Direct Uplink Bypassing Backhaul Delays
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Solution Overview
Problem
In LTE-A systems, the non-ideal backhaul between eNBs leads to delayed HARQ feedbacks, causing throughput degradation and operational issues due to incorrect retransmissions, as eNBs struggle to receive HARQ feedbacks immediately and synchronize resource indices for transmitting feedbacks.
Innovation Solution
A method where HARQ feedbacks are transmitted to a first base station based on downlink control information, with specific PUCCH resource determination and formatting to ensure timely detection and forwarding, even when feedbacks are triggered by packets from different base stations, thereby overcoming backhaul delays and resource synchronization challenges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedbacks are transmitted via backhaul between eNBs, then the feedback can be forwarded to the correct destination, but the backhaul delay causes delayed feedback reception and throughput degradation
Solution Approach 1:
The patent segments the HARQ feedback transmission path by introducing a direct uplink transmission channel from UE to eNB, bypassing the backhaul segment. This allows feedback to be sent directly without waiting for backhaul delivery, resolving the delay issue while maintaining reliability through alternative routing.
Solution Approach 2:
The patent uses the uplink control channel as an intermediary path for HARQ feedback transmission. Instead of relying solely on the backhaul intermediary, the feedback can travel through the uplink channel intermediary, providing a faster route that avoids backhaul delays while ensuring reliable delivery to the destination eNB.
2Adaptability or versatility
If eNBs use non-ideal backhaul for communication, then connectivity between eNBs is maintained, but resource synchronization becomes difficult and incorrect retransmissions occur
Solution Approach 1:
The patent implements a feedback mechanism where the serving eNB receives HARQ feedback directly from the UE and can immediately determine whether retransmission is needed. This direct feedback loop eliminates the synchronization issues caused by backhaul delays, as the serving eNB has real-time information about packet reception status and can make accurate retransmission decisions without relying on delayed information from the forwarding eNB.
Data Source
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AI summary
A method of transmitting hybrid automatic repeat request (HARQ) feedbacks for a communication device comprises transmitting at least one first HARQ feedback to a first base station according to first downlink (DL) control information (DCI) indicating at least one first DL packet, if the at least one first HARQ feedback is at least triggered by the at least one first DL packet, wherein the at least one first DL packet is transmitted by the first base station to the communication device; and transmitting at least one second HARQ feedback to the first base station, if the at least one second HARQ feedback is only triggered by at least one second DL packet, wherein the at least one second DL packet is transmitted by a second base station to the communication device.