CoMP Base Station HARQ ACK Coordination to Prevent Resource Wastage
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Solution Overview
Problem
In Coordinated Multi-Point (CoMP) communication systems, base stations within a CoMP cooperating set may fail to receive ACK from a user terminal, leading to resource wastage due to unnecessary retransmissions during HARQ processes.
Innovation Solution
Each base station in the CoMP cooperating set transmits ACK information to other base stations upon receiving HARQ ACK from the user terminal, and performs retransmissions only if the maximum retransmission number has not been reached and no ACK information is received from other base stations, using the same communication resource as the initial transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple base stations in a CoMP cooperating set independently perform HARQ retransmission without ACK information sharing, then each base station can ensure its own data transmission reliability, but resource wastage occurs due to unnecessary retransmissions when ACK is not received
Solution Approach 1:
The patent merges the ACK reception status of multiple base stations by having them share ACK information through inter-base station communication. When any base station receives an ACK from the user terminal, it notifies other base stations in the CoMP cooperating set, allowing them to stop retransmission. This combining approach resolves the contradiction by maintaining reliability through coordinated retransmission control while eliminating resource wastage from duplicate retransmissions.
Solution Approach 2:
The patent introduces a feedback mechanism where base stations exchange ACK reception status information with each other. Each base station not only receives ACK from the user terminal but also provides feedback to other base stations about the ACK status. This feedback loop enables all base stations to make informed retransmission decisions, preventing unnecessary retransmissions while ensuring reliable data delivery.
2Loss of energy
If base stations share ACK information through inter-base station communication, then resource wastage from unnecessary retransmissions is prevented, but system complexity increases due to additional communication overhead
Solution Approach 1:
The patent segments the ACK information sharing function into a modular communication mechanism between base stations. Instead of requiring complex coordinated retransmission control across all base stations simultaneously, the system divides the problem into independent ACK reception events, where each base station independently notifies others of ACK receipt. This segmentation reduces system complexity by breaking down the coordination problem into manageable, event-driven notifications.
3Speed
If base stations perform HARQ retransmission independently without coordination, then retransmission response time is fast, but resource utilization efficiency deteriorates due to redundant retransmissions
Solution Approach 1:
The patent applies preliminary action by having base stations pre-establish the ACK information sharing mechanism before retransmission occurs. When ACK information is received, the notification to other base stations happens immediately, allowing them to proactively cancel scheduled retransmissions. This preliminary coordination prevents the need for complex post-retransmission coordination, maintaining fast response times while improving resource utilization efficiency.
Data Source
AI summary
In a mobile communication system in which a plurality of base stations included in a CoMP cooperating set perform downlink CoMP communication with a user terminal, when receiving HARQ ACK from the user terminal, each of the plurality of base stations transmits ACK information on the received HARQ ACK to another base station included in the CoMP cooperating set.