Downlink Scheduling Using Channel Measurement Sub-frames
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In LTE/LTE-A wireless communication systems, the delay in feedback information from user equipment (UE) to base stations leads to inaccurate resource allocation, causing unreliable feedback and mismatch between scheduled and actual channel conditions, resulting in unstable inter-cell interference.
Innovation Solution
Implement a scheduling method where base stations use the most recently received feedback information from UEs during channel measurement sub-frames and store the corresponding scheduling results for later use, ensuring accurate resource allocation and reduced inter-cell interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If base stations use delayed feedback information for resource allocation, then resource allocation can be performed, but the feedback information becomes inaccurate and does not match actual channel conditions
Solution Approach 1:
The system performs channel measurement in advance during specific sub-frames (0 and 5) before actual resource allocation occurs. The UE calculates feedback information based on reference signals or data symbols transmitted in these measurement sub-frames, allowing the base station to have accurate channel state information ready before scheduling decisions are made in subsequent sub-frames.
Solution Approach 2:
The radio frame is divided into different types of sub-frames with specific functions: channel measurement sub-frames (0 and 5) for feedback calculation, and other sub-frames (1-4, 6-9) for actual resource allocation. This segmentation allows the system to separate the feedback generation process from the resource allocation process, ensuring that feedback is always based on current channel conditions while allocation can occur at optimal times.
2Duration of action of moving object
If feedback information is transmitted with delay, then transmission can be completed, but the feedback becomes unreliable for current channel conditions
Solution Approach 1:
The UE performs channel measurement and calculates feedback information in advance during measurement sub-frames before actual data transmission begins. This preliminary feedback calculation ensures that when the base station receives the feedback, it reflects the current channel conditions rather than outdated information from previous transmissions.
Solution Approach 2:
The system uses periodic channel measurement sub-frames (specifically sub-frames 0 and 5 in each 10ms radio frame) to refresh the feedback information. This periodic refresh ensures that the base station receives updated channel state information regularly, maintaining reliability even as channel conditions change over time.
3Ease of operation
If resource allocation is performed based on outdated feedback, then scheduling can proceed, but inter-cell interference becomes unstable
Solution Approach 1:
The base station performs resource allocation using feedback information that was calculated in the same measurement sub-frame, ensuring that the allocation is based on current and accurate channel conditions. This preliminary alignment between feedback generation and allocation timing prevents mismatches that would cause unstable interference patterns.
Solution Approach 2:
The system implements a tight feedback loop where the base station receives feedback from UE, processes it immediately for resource allocation in the same sub-frame, and the allocated resources are used for transmission. This real-time feedback mechanism ensures that resource allocation continuously adapts to current channel conditions, stabilizing inter-cell interference through coordinated scheduling decisions.
Data Source
AI summary
The present invention relates to method and apparatus for scheduling downlink transmission. According to an embodiment of the present invention, a method for scheduling downlink transmission in a wireless communication system is provided. The method comprises: scheduling, in a channel measurement sub-frame, user equipments in a cell according to feedback information that was most recently received from the user equipments, wherein in the channel measurement sub-frame, the user equipments calculate feedback information to be reported; and scheduling, in response to receipt of the feedback information, the user equipments based on a result of scheduling corresponding to the channel measurement sub-frame. According to an embodiment of the present invention, there is also provided a scheduling apparatus, base station device and corresponding computer program product.