Base Station ABS Pattern Switching Delay Prevention
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Solution Overview
Problem
The conventional inter-cell interference control technique using ABS in mobile communication systems can cause communication delays during HARQ retransmissions when the ABS pattern changes, leading to ARQ retransmissions due to switched subframes where signal transmission is not performed.
Innovation Solution
A base station apparatus that adapts the MCS index value through adaptive modulation control before switching the ABS pattern, ensuring communication completion or HARQ retransmission within a predetermined period, thereby preventing communication delays by changing the MCS index based on remaining transmittable times and maintaining resource allocation for HARQ retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ABS pattern is switched to reduce inter-cell interference, then interference between macro-cell and small-cell base stations is reduced, but HARQ retransmission may fail when the retransmission subframe switches to an ABS subframe, causing communication delay
Solution Approach 1:
The base station determines in advance which subframes will be ABS subframes in future patterns, and identifies subframes where HARQ retransmission should be prohibited before the pattern switching occurs. By proactively marking these subframes as prohibited for HARQ retransmission, the system ensures that HARQ processes do not schedule retransmissions in subframes that will become ABS subframes, thus preventing HARQ retransmission failures while maintaining the interference reduction benefits of ABS pattern switching
Solution Approach 2:
The system implements a feedback mechanism where the base station monitors the ABS pattern configuration and HARQ scheduling status, and dynamically adjusts the prohibited subframe list for HARQ retransmission. When the ABS pattern is updated, the base station recalculates which subframes should be prohibited for HARQ retransmission and notifies relevant entities, ensuring that the HARQ process adapts to the new pattern while maintaining reliable retransmission
2Speed
If HARQ retransmission is performed in subframes before ABS pattern switching, then communication speed is maintained, but the subframe may switch to ABS subframe during retransmission period, causing the retransmission to fail
Solution Approach 1:
The base station proactively determines and marks prohibited subframes for HARQ retransmission before the ABS pattern switching occurs. By identifying in advance which subframes will become ABS subframes and marking them as prohibited for HARQ retransmission, the system prevents scheduling conflicts that would cause retransmission failures, thereby maintaining both communication speed and reliability
Solution Approach 2:
The system applies a preliminary countermeasure by prohibiting HARQ retransmission in specific subframes that are predicted to become ABS subframes. This preemptive prohibition prevents the harmful effect of scheduling retransmissions in subframes where transmission is not performed, thus avoiding communication delays while maintaining the interference reduction benefits of ABS pattern switching
Data Source
AI summary
A base station apparatus capable of preventing occurrence of a communication delay when performing an inter-cell interference control using an ABS is provided. The base station apparatus is capable of performing an inter-cell interference control by setting an ABS pattern with one cycle of a predetermined number of subframes, and when the ABS pattern is to be switched, changes an MCS (Modulation and Coding Scheme) index value to be determined by an adaptive modulation control, for a communication within a predetermined period of time on or before a switching time of the switching, with respect to a subframe in which a communication with a mobile station apparatus is allowed before switching the ABS pattern.