Control Signaling for Non-Codebook Beamforming
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Solution Overview
Problem
Modern communications systems, particularly those with high path loss at millimeter wavelength frequencies, face increased complexity due to the need for additional overhead to determine optimal precoders for beamformed communications, which complicates the process of maximizing signal gain.
Innovation Solution
A system and method for control signaling that involves configuring channel state information reference signal (CSI-RS) and sounding reference signal (SRS) resources, allowing devices to determine precoders based on downlink reference signals, enabling non-codebook based beamformed transmission by sending and receiving control information to facilitate precoder selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beamforming is used to improve signal gain in high path loss environments, then communication performance is improved, but system complexity increases due to additional overhead for determining precoders
Solution Approach 1:
The patent applies preliminary action by having the access node send downlink reference signals (DL RS) and configuration information to the UE in advance, enabling the UE to determine precoders before uplink transmission. This allows the UE to perform measurements and calculate precoding matrices based on received DL RS, eliminating the need for complex real-time interactions during transmission.
Solution Approach 2:
The patent implements self-service by enabling the UE to autonomously determine precoders using the received downlink reference signals and configuration information. The UE independently performs measurements, calculates precoding matrices, and applies them to uplink transmissions without requiring the access node to explicitly signal or control the precoder selection process.
2Power
If additional overhead is used to determine optimal precoders, then signal gain is maximized, but control signaling complexity increases
Solution Approach 1:
The patent extracts the essential information needed for precoder determination by having the access node send only the necessary configuration parameters and downlink reference signals, rather than transmitting complete precoder matrices or extensive control information. The UE derives the remaining information independently through measurements and calculations.
Solution Approach 2:
The patent uses copying by having the UE replicate the downlink channel characteristics observed from DL RS measurements and apply them to uplink precoding. The UE creates a copy of the channel state information and uses it to determine appropriate precoders for uplink transmission, avoiding the need for explicit feedback of channel information.
3Ease of operation
If non-codebook based beamformed transmission is implemented, then precoder determination is simplified, but additional control signaling is required to facilitate the process
Solution Approach 1:
The patent merges the configuration of SRS resources and DL RS resources into a single control signaling message, and combines the triggering of SRS transmission with the indication of associated DL RS resources. This consolidation reduces the number of separate control messages needed while still providing all necessary information for non-codebook based beamforming.
Data Source
AI summary
A method for operating an access node includes sending a configuration of one or more first channel state information reference signal (CSI-RS) resources and a configuration of one or more sounding reference signal (SRS) resources, generating first control information including an identifier of a SRS resource set that includes the one or more SRS resources precoded by one or more precoders, generating second control information including an identifier of the one or more first CSI-RS resources, wherein the one or more first CSI-RS resources are associated with the identified SRS resource set, wherein the one or more first CSI-RS resources convey a downlink reference signal (RS) used for making measurements, and wherein the one or more precoders are determined in accordance with measurements of the downlink RS, sending the first control information and the second control information, and sending the downlink RS.