Closed-Loop Antenna Selection Using SRS Feedback in 5G Uplink MIMO
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Solution Overview
Problem
Existing 5G wireless communication systems lack flexibility and efficiency in antenna selection due to limitations in uplink multiple-input multiple-output (MIMO) frameworks, particularly in cases where the number of transmit chains is less than the number of antennas, leading to mismatches between uplink and downlink channels.
Innovation Solution
Implementing closed-loop antenna selection by transmitting UE capability information for the number of sounding reference signals (SRSs) and receive SRS configurations, allowing the network node to indicate antenna associations for optimal antenna selection, enhancing flexibility and reducing limitations in existing MIMO frameworks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of transmit chains is less than the number of antennas, then device complexity is reduced, but antenna selection flexibility and communication performance deteriorate due to mismatches between uplink and downlink channels
Solution Approach 1:
The patent implements closed-loop antenna selection where the UE transmits SRS signals through different antenna-chain combinations, the network node measures channel quality, and feeds back antenna selection indications to the UE. This feedback mechanism enables the system to adapt antenna selections based on actual channel conditions, resolving the flexibility issue despite having fewer transmit chains than antennas.
Solution Approach 2:
The patent enables dynamic antenna selection where the mapping between transmit chains and antennas can change based on channel conditions. The network node can dynamically indicate different antenna associations for different SRS resources, allowing the system to adaptively select optimal antenna-chain combinations rather than being fixed, thus improving flexibility without increasing hardware complexity.
2Device complexity
If existing MIMO frameworks are used with fixed antenna mappings, then device complexity is maintained low, but communication performance deteriorates due to mismatches between uplink and downlink channels
Solution Approach 1:
The patent segments the antenna-chain mappings into different configurations that can be independently selected. By dividing the antenna selection into discrete SRS resources with different antenna associations, the system can choose optimal segmentations based on channel conditions without requiring complete redesign of the MIMO framework, thus maintaining low complexity while improving reliability.
Solution Approach 2:
The patent changes the parameter of antenna-chain mapping from fixed to variable based on channel conditions. By allowing the mapping parameters to be dynamically adjusted through closed-loop feedback, the system adapts to channel variations and improves communication performance without fundamentally changing the MIMO framework structure, maintaining implementation simplicity.
3Adaptability or versatility
If closed-loop antenna selection is implemented, then antenna selection flexibility and communication performance improve, but device complexity and signaling overhead increase
Solution Approach 1:
The patent makes the SRS transmission mechanism universal by enabling it to serve multiple purposes: channel measurement, antenna selection, and feedback generation. By making the existing SRS framework multi-functional for antenna selection purposes, the system avoids adding separate complex mechanisms, thus improving flexibility while limiting the increase in overall system complexity.
Solution Approach 2:
The patent implements partial closed-loop antenna selection where not all possible antenna combinations need to be tested simultaneously. By selecting a representative subset of antenna-chain combinations for SRS transmission and using the feedback from these partial measurements to guide future selections, the system achieves sufficient flexibility without the full complexity of exhaustive search methods.
Data Source
AI summary
Aspects described herein relate to transmitting user equipment (UE) capability information related to a number of sounding reference signals (SRSs) to transmit for a number of antennas and a number of transmit chains at the UE, receiving a SRS configuration of SRS resources for transmitting the number of SRSs, transmitting the number of SRSs over the SRS resources, and receiving an antenna selection indication related to a set of one or more of the number of antennas to be associated to the number of transmit chains for performing antenna selection at the UE. Other aspects relate to receiving UE capability information, transmitting the SRS configuration, receiving the SRSs, and transmitting the antenna selection information.