Rank Adaptation via Power Measurement Offset in MIMO Systems
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Solution Overview
Problem
In multiple-antenna wireless communication systems, existing technologies face challenges in accurately adapting transmission rank due to imperfect channel quality indicators (CQIs) and interference, leading to suboptimal performance and interference issues.
Innovation Solution
The introduction of configurable Power Measurement Offset (PMO) parameters and scaling factors allows for balanced feedback that considers both receiving node performance and overall system performance, enabling more accurate rank adaptation by modifying the relative candidate strengths of different ranks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the receiving node selects higher transmission ranks to improve data rates, then the data rate increases, but interference to other users increases
Solution Approach 1:
The patent introduces PMO parameters that modify the CQI values based on the assumed transmitted energy for data relative to reference signals. By adjusting these parameters, the system changes the effective threshold for rank selection, allowing the receiving node to select ranks that balance its own data rate requirements with system-wide interference considerations
Solution Approach 2:
The patent implements a feedback mechanism where the receiving node reports not just the selected rank but also PMO parameters to the sending node. The sending node uses this feedback to adjust its transmission strategy, creating a closed-loop system that optimizes both data rate and interference management through iterative adjustments
2Reliability
If the receiving node reports higher ranks based on channel measurements, then the receiving node's performance improves, but overall system performance deteriorates due to increased interference
Solution Approach 1:
The patent modifies the CQI reporting mechanism by introducing PMO parameters that scale the reported channel quality based on the assumed energy relationship between data and reference signals. This transformation allows the receiving node to report ranks that reflect system-wide performance rather than just individual link quality
Solution Approach 2:
The PMO parameters act as an intermediary that translates the receiving node's channel measurements into system-optimized rank recommendations. These parameters mediate between the receiving node's performance goals and the overall system performance requirements by adjusting the mapping between measured channel quality and reported rank
3Productivity
If the sending node uses channel dependent precoding to focus transmit energy, then the data rate increases, but the complexity of precoder selection increases
Solution Approach 1:
The patent changes the precoder selection approach by using PMO parameters to simplify the criteria for selecting precoders from the codebook. Instead of complex optimization, the system uses the PMO-adjusted CQI values to directly determine suitable precoders, reducing computational complexity while maintaining data rate performance
Solution Approach 2:
The patent employs a codebook of pre-defined precoder matrices that can be selected based on simple PMO-parameter-adjusted criteria. Rather than computing optimal precoders in real-time, the system uses a finite set of pre-computed precoders, trading off some optimality for significantly reduced complexity and faster selection
Data Source
AI summary
The invention relates to methods and arrangements for rank adaptation for transmissions over a multipie-input-muttipie-output, M1MO, channel in a wireless communications system. A receiving node (270) performs (310) measurements on reference signals received from a sending node (200), The receiving node performs (330a(330b) a first feedback computation for a first rank and at least one second feedback computation for at yeast one second rank based on the measurements. The first feedback computation includes applying a first relation between assumed transmitted energy for data and transmitted energy for the reference signals that is specific to the first rank. A second relation between assumed transmitted energy for data and transmitted energy for the reference signals is specific to the at least one second rank. The receiving node selects (340) one rank based on the feedback computations and indicates (350) the selected rank in a feedback report to the sending node.