Flexible Frame Beamforming Training for NR Access
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Solution Overview
Problem
Current network access procedures in LTE and NR systems lack support for beamforming based access, particularly in idle states, and fail to efficiently manage beamforming training and CSI acquisition in active states.
Innovation Solution
The proposed solution involves an apparatus and method for beamforming training in NR systems, which includes monitoring beamforming training reference signals (BT-RS) and physical broadcast channels (PBCH) to acquire symbol and subframe timing, and transmitting beam ID feedback with a unique training sequence to establish an RRC connection. This enables efficient beamforming training and CSI acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If omni-directional or sector-based transmission is used for network access, then existing access procedures can be maintained, but beamforming based access functions are not supported
Solution Approach 1:
The access procedure is segmented into distinct phases: initial omni-directional/sector-based access for basic connectivity, followed by beamforming training phases for beam pair determination. This segmentation allows the system to maintain backward compatibility while adding beamforming capabilities in a structured manner.
Solution Approach 2:
Beamforming training reference signals are transmitted before actual data transmission to establish beam pairs in advance. This preliminary beamforming training enables the system to determine optimal beam pairs during idle state before transitioning to connected state, avoiding the need for complex real-time beam switching during data transmission.
2Adaptability or versatility
If beamforming training is performed in RRC_Connected states, then beamforming capabilities can be utilized, but existing frame structures lack support for such procedures
Solution Approach 1:
The frame structure is designed to be dynamic and flexible, allowing insertion of beamforming training reference signals at configurable intervals during RRC_Connected states. The frame structure can adapt its timing and resource allocation based on mobility conditions and beamforming training requirements, rather than being fixed.
Solution Approach 2:
The flexible frame structure serves multiple functions: it supports both traditional LTE data transmission and beamforming training procedures. The same frame structure can accommodate beamforming training reference signals, data channels, and control channels, making it a universal framework for both legacy and advanced features.
3Reliability
If CSI-RS and SRS configurations are designed for different usages, then downlink and uplink requirements can be met, but UE awareness of configurations for different usages becomes complex
Solution Approach 1:
The system implements feedback mechanisms where the UE reports channel state information and beam quality measurements back to the network. Based on this feedback, the network dynamically adjusts and signals the appropriate CSI-RS and SRS configurations to the UE, reducing the complexity of configuration management by making it adaptive rather than static.
Solution Approach 2:
The UE autonomously performs beam measurements and selects optimal beam pairs based on received reference signals, then reports these selections to the network. This self-service approach reduces the need for complex network-controlled configuration signaling, as the UE independently manages its beamforming parameters based on channel conditions.
4Ease of operation
If minimum system information is periodically broadcast in all cells, then initial access information is available, but issues arise regarding cell coverage and UE camping decisions
Solution Approach 1:
Beamforming training reference signals are transmitted periodically in advance to allow UEs to perform beam measurements and assess cell quality before making camping decisions. This preliminary beam-based measurement enables more reliable determination of whether a cell is suitable for camping, beyond just checking the presence of minimum system information.
Solution Approach 2:
The system replaces the traditional mechanical approach of relying solely on omnidirectional system information broadcast with beamforming-based directional signal transmission. This allows the network to target specific geographic areas with beamformed reference signals, providing more accurate cell coverage information to UEs in those directions while reducing unnecessary broadcasts in other directions.
Data Source
AI summary
The present application is at least directed to an apparatus on a network including a non-transitory memory including instructions stored thereon for beamforming training. The apparatus also includes a processor, operably coupled to the non-transitory memory, capable of executing the instructions of monitoring a first beamforming training reference signal (BT-RS) and physical broadcast channel (PBCH) of a network node to acquire symbol timing and subframe timing, where a common part of the PBCH includes a first beam ID. The processor is also configured to execute the instructions of transmitting, to the network node, a beam ID feedback with a unique training sequence generated based on the first beam ID to establish a radio resource control (RRC) connection. The processor is further configured to execute the instructions of receiving, from the network node, a second BT-RS to perform beamforming training. The processor even further is configured to execute the instructions of receiving, from the network node, downlink control information (DCI) carrying one or more second beam IDs. The one or more second beam IDs are associated with one or more beams configured via RRC signaling. Resources of the second BT-RS are configured by a RRC message via the RRC connection.