Downlink Common Pilot Insertion in TDD OFDMA Systems
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Solution Overview
Problem
In TDD systems based on OFDMA, the existing method of including a downlink common pilot in each slot is not adaptable, leading to excessive system overhead due to the lack of necessary uplink feedback, which hinders efficient frequency domain scheduling.
Innovation Solution
A method is introduced to divide data into segments transmitted in continuous time periods, with a common pilot inserted in one downlink slot within each time period, ensuring that each downlink slot belongs to a specific scheduling time period, thereby optimizing system resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a downlink common pilot is inserted in each downlink slot, then users can perform frequency domain scheduling and select optimal sub frequency bands, but system overhead becomes excessive due to lack of necessary uplink feedback
Solution Approach 1:
The patent segments the continuous downlink transmission into discrete scheduling time periods, each containing multiple downlink slots and one uplink slot. The common pilot is inserted only in specific downlink slots within each time period rather than every downlink slot, reducing overhead while maintaining scheduling capability. This segmentation allows the system to balance between providing sufficient pilot signals for frequency domain scheduling and minimizing system overhead.
2Measurement precision
If a downlink common pilot is inserted in each slot, then channel quality measurement can be performed for each sub frequency band, but resource occupancy increases significantly
Solution Approach 1:
The patent applies partial action by inserting the common pilot in only certain downlink slots within each scheduling time period rather than in every downlink slot. This partial insertion provides sufficient channel quality measurement capability for frequency domain scheduling while avoiding the excessive resource occupancy that would result from inserting pilots in every slot. The selective placement of pilots achieves the necessary measurement precision with reduced resource consumption.
Data Source
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AI summary
The present invention discloses a method for inserting a downlink common pilot in a TDD system and more particularly to a method for inserting a downlink common pilot in a TDD system based on OFDMA technology and the method includes two steps. A: data to be transmitted are divided into several segments to be transmitted in several continuous time periods, wherein each time period includes several slots with at least one downlink slot; B: a common pilot is inserted in one downlink slot in the time period. Therefore, the scheduling based on the frequency domain can be achieved by measuring the common pilot channel.