Relay Node Acknowledgement Timing via R-PDCCH
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Solution Overview
Problem
Relay network nodes in mobile telecommunication systems face challenges in delivering acknowledgement messages related to ARQ processes, as they lack a defined timing relation for HARQ feedback, leading to non-adaptive re-transmissions and increased network load.
Innovation Solution
Establishing a predetermined timing relation between the delivery of acknowledgement messages from the first protocol layer to the second protocol layer, using time slots or intervals associated with ARQ processes, and providing additional information such as ARQ process identifiers or time offsets to correctly associate acknowledgements with corresponding ARQ processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If relay nodes use regular PHICH feedback timing for uplink transmissions, then acknowledgement delivery timing can be determined, but PHICH is not defined for relay node connections to donor eNB
Solution Approach 1:
The patent introduces R-PDCCH as an intermediary control channel that carries both uplink grants and implicit acknowledgement information for relay nodes. Instead of directly using PHICH which is not defined for RN-eNB connections, the R-PDCCH serves as a mediator that combines grant and ACK functionality, allowing relay nodes to receive acknowledgements through the same channel used for scheduling.
2Productivity
If relay nodes send uplink data without defined ACK timing, then data transmission can proceed, but non-adaptive re-transmissions occur increasing network load
Solution Approach 1:
The patent implements a feedback mechanism where the donor eNB sends acknowledgement information embedded in R-PDCCH downlink assignments. The relay node monitors these assignments to determine whether its uplink transmissions were successfully received, enabling adaptive re-transmission decisions. This feedback loop prevents unnecessary re-transmissions and optimizes network resource usage.
3Reliability
If relay nodes implement internal ACK sending to MAC layer, then acknowledgement delivery is achieved, but ARQ process association requires additional timing relations
Solution Approach 1:
The patent establishes predetermined timing relations between uplink data transmissions and the corresponding R-PDCCH acknowledgements. By defining these timing relationships in advance (e.g., ACK sent in specific subsequent downlink subframes), the relay node and donor eNB can associate acknowledgements with the correct ARQ processes without complex real-time determination, reducing operational complexity.
Data Source
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AI summary
The invention proposes a novel method for handling acknowledgement messages between a first protocol layer (L1) and a second protocol layer (L2) in a network node operating as a relay network node (RN). The first protocol layer (L1) is lower with respect to the second protocol layer (L2). The acknowledgement messages (ACK) are related to Automatic Repeat Request (ARQ) processes and the Relay Node (RN) is engaged in an Uplink transmission towards a network access node (eNB). The method comprises a step (10) of receiving a first grant indication by said network access node (eNB) that an Uplink Transmission is granted at said first protocol layer entity (L1) and a step of sending (100) towards said second protocol layer entity (L2) an indication of Acknowledgement (ACK) after receiving a first grant indication. The invention also proposes a corresponding Relay Node (RN).