Uplink Transmission Rate via Cross-Layer HARQ Coordination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems, such as LTE, face inefficiencies in uplink transmission rates due to interference-related errors in HARQ retransmissions, where ACKs/NACKs can be misinterpreted, leading to unnecessary retransmissions and dropped packets, and lack of coordination between MAC and RLC layers for error correction.
Innovation Solution
Implementing cross-layer coordination between the MAC and RLC layers to consider the robust acknowledgement status from the RLC layer when making retransmission decisions at the MAC layer, thereby reducing errors and improving throughput by leveraging the accuracy of ARQ mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If HARQ retransmission mechanism is used at MAC layer, then fast retransmission is achieved, but interference causes ACK/NACK misinterpretation leading to erroneous retransmissions
Solution Approach 1:
The patent introduces RLC layer acknowledgement status as an intermediary indicator to help MAC layer make more accurate retransmission decisions. The RLC layer's more robust acknowledgement mechanism acts as a mediator between the PHY layer transmission and the MAC layer retransmission control, reducing erroneous retransmissions caused by PHICH interference.
Solution Approach 2:
The patent enhances the feedback mechanism by incorporating RLC layer acknowledgement status into the MAC layer's retransmission decision process. This multi-level feedback system allows the MAC layer to verify whether a NACK received from PHICH is accurate before initiating retransmission, thereby reducing false retransmissions.
2Reliability
If ARQ mechanism is used at RLC layer, then transmission accuracy is improved, but retransmission speed decreases and throughput is reduced
Solution Approach 1:
The patent applies partial action by having the MAC layer perform fast HARQ retransmission when PHICH indicates NACK, but then verify with RLC layer status before finalizing the retransmission decision. This partial use of ARQ verification at the MAC layer reduces unnecessary retransmissions without requiring full ARQ processing for all cases, thus maintaining throughput while improving accuracy.
3Device complexity
If MAC layer operates independently without RLC layer coordination, then device complexity is reduced, but erroneous retransmissions increase due to lack of feedback
Solution Approach 1:
The patent merges the MAC layer and RLC layer acknowledgement mechanisms by having the MAC layer consider both PHICH status and RLC layer acknowledgement status when making retransmission decisions. This integration combines the fast retransmission capability of MAC layer with the accuracy of RLC layer without requiring complete system redesign.
Data Source
AI summary
A method for improving uplink transmission rate in a wireless communication device is provided. The wireless communication device can include a first logical layer and a second logical layer. The method can include the wireless communication device decoding, at the first logical layer, a first acknowledgement status of a transmitted data unit. The method can further include the wireless communication device determining, at the first logical layer, a second acknowledgement status of the data unit, which can be an acknowledgement status of the data unit at the second logical layer. The method can additionally include the wireless communication device determining, at the first logical layer, whether to retransmit the data unit based at least in part on both the first acknowledgement status of the data unit and the second acknowledgement status of the data unit.