Differential CQI Signaling for Multi-Beam MIMO Systems
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Solution Overview
Problem
In multi-beam MIMO systems, the high signaling load of channel quality information (CQI) required for each beam increases with the number of beams, leading to inefficiencies in transmission rate control.
Innovation Solution
The method involves determining primary and secondary beams with different qualities, where the primary beam has a higher quality and secondary beams have lower qualities, and using differential signaling to reduce the CQI signaling overhead by signaling absolute values for the primary beam and relative offsets for secondary beams, along with varying update rates, cut-off thresholds, and quantization granularities based on beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are transmitted simultaneously in MIMO systems, then transmission capacity and diversity are improved, but CQI signaling load increases
Solution Approach 1:
The patent extracts only the essential CQI information needed for secondary beams by using differential signaling. Instead of transmitting full CQI values for all beams, the system extracts and transmits only the difference (offset) between primary and secondary beam CQI values, significantly reducing signaling load while maintaining necessary control capability.
Solution Approach 2:
The patent transitions from absolute CQI signaling to differential CQI signaling, changing the dimension of information representation. By signaling CQI offsets relative to a primary beam rather than absolute values for each beam, the system reduces the signaling dimension and associated overhead.
2Measurement precision
If absolute CQI values are signaled for all beams, then transmission rate control precision is improved, but signaling overhead increases
Solution Approach 1:
The patent applies different signaling qualities to different beams based on their importance and channel conditions. Primary beams use absolute CQI signaling for high precision, while secondary beams use differential CQI signaling with offsets, allocating signaling resources locally according to each beam's requirements rather than applying a uniform approach.
Solution Approach 2:
The patent changes the CQI signaling parameter from absolute values to differential offsets for secondary beams. This parameter transformation reduces the number of bits required for signaling while maintaining sufficient precision for rate control, as the CQI variations between beams are typically smaller than absolute CQI values.
Data Source
AI summary
The present invention relates to the signaling of channel quality information in a multi-beam transmission system, wherein a plurality of beams are simultaneously transmitted and a plurality of sets of channel quality information are transmitted for controlling independently the transmission rate on the different beams. Determined are beams with a different quality resulting in different effects of errors in the transmissions of the channel quality information for the beams. Said different effects are exploited for reducing a signaling overhead of the channel quality information for the beams.