Sub-band CSI Transmission Order Inversion for Wireless Systems
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Solution Overview
Problem
In wireless communication systems with extended multi-antenna configurations, the conventional method of channel state information (CSI) measurement using CSI-RS intermittently transmitted does not accurately reflect the actual channel state, leading to errors and inefficient resource utilization.
Innovation Solution
A method and device for transmitting and receiving CSI, where sub-band CSI is generated and transmitted sequentially to the base station, with the order of transmission differing from the initial sequence, using a cyclic shift or reverse order scheme to reduce errors and improve resource efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If CSI-RS is intermittently transmitted to reduce reference signal overhead, then resource efficiency is improved, but channel state measurement accuracy deteriorates
Solution Approach 1:
The patent segments the frequency band into multiple sub-bands and transmits CSI-RS at different time instances for each sub-band. The terminal measures channel state in each sub-band at different times and combines the measurements to obtain the overall channel state. This segmentation allows intermittent transmission while maintaining accuracy through temporal diversity across sub-bands.
Solution Approach 2:
The patent performs preliminary channel state measurement for each sub-band at different time instances before the actual CSI feedback is needed. By measuring channel state in advance for each sub-band and storing these measurements, the terminal can later combine these preliminary measurements to obtain accurate channel state information even when CSI-RS is transmitted intermittently.
2Ease of operation
If sub-band CSI is transmitted sequentially in fixed order, then transmission simplicity is maintained, but CSI error accumulates in later sub-bands
Solution Approach 1:
The patent dynamically changes the transmission order of sub-band CSI feedback. Instead of a fixed sequential order, the terminal transmits sub-band CSI in a variable order based on the timing of CSI-RS transmission and measurement completion. This dynamic ordering prevents systematic error accumulation in later sub-bands by distributing the measurement age across different sub-bands.
Solution Approach 2:
The patent inverts the conventional fixed sequential transmission order by using reverse or variable ordering. The terminal may transmit sub-band CSI in reverse order (from last sub-band to first) or in a shuffled order based on when the channel state measurement was taken. This inversion prevents the systematic bias where later sub-bands always have older measurements.
Data Source
AI summary
The present invention relates to a wireless communication system, and more particularly, to a method and device for transmitting/receiving channel state information (CSI). A method for a terminal for transmitting CSI according to one embodiment of the present invention includes: a first step of receiving a reference signal for channel measurement from a base station; a second step of generating sub-band (SB) CSI for each of a plurality of SBs using the received reference signal in the terminal and sequentially transmitting the generated SB CSI to a base station; and a third step of sequentially transmitting each SB CSI to a base station according to an order different from that of the sequential transmission.