Directional Beam Training Using Spreading Sequences
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional beamforming systems face high training overhead due to the need for exhaustive search methods in hybrid beamforming structures, which are inefficient and become even more challenging with multiple user equipment in cellular systems.
Innovation Solution
The system generates multiple directional beams, modulates them using spreading sequences to enlarge their range, and uses these modulated beams as training-specific beams, sweeping them with a plurality of antennas to reduce the number of required samples by exploiting the sparse nature of high-frequency channels, thereby reducing training overhead through compressive sensing algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exhaustive search method is used to sweep all possible directions, then channel knowledge can be obtained with required resolution, but training overhead increases linearly with the number of antennas
Solution Approach 1:
The patent segments the channel estimation process into two stages: first estimating angles-of-arrival at the receiver using a reduced set of beams, then using these estimates to guide the transmitter's beam sweeping. This segmentation divides the exhaustive search into manageable parts, reducing the total number of beams that need to be swept at the transmitter while maintaining required resolution.
Solution Approach 2:
The patent performs preliminary channel estimation at the receiver before the transmitter completes its full beam sweep. By obtaining angle estimates in advance, the system can focus subsequent transmitter beams more efficiently, avoiding the need to sweep all possible directions with full precision and thereby reducing training overhead.
2Loss of time
If hierarchical search method is used with multi-resolution beam-codebooks, then training overhead increases with log of number of antennas, but feedback channel requirements increase and control plane complexity increases
Solution Approach 1:
The patent extracts the angle estimation function from the feedback channel and performs it locally at the receiver using downlink reference signals. By taking out this functionality from the feedback path, the system reduces control plane complexity and feedback requirements while maintaining efficient beam training through the two-stage approach.
3Device complexity
If hybrid beamforming structure is used to reduce fabrication cost and energy consumption, then number of RF-chains is limited, but baseband cannot directly observe the entire channel dimension
Solution Approach 1:
The patent introduces angle-of-arrival estimates as an intermediary representation of channel information. Instead of requiring the baseband to directly observe the entire channel dimension, the system uses these angle estimates as a compact intermediary that captures essential channel characteristics, enabling efficient beam training with limited RF-chains.
4Adaptability or versatility
If beam training is performed for multiple user equipment in the same cell, then channel knowledge can be acquired for all users, but training overhead grows linearly with the number of user equipment
Solution Approach 1:
The patent merges the beam training processes for multiple users by performing receiver-side angle estimation simultaneously for all users during downlink reference signal reception. This combining approach allows the system to acquire channel knowledge for multiple users in parallel at the receiver, avoiding linear scaling of training overhead with the number of users.
Data Source
AI summary
A system for acquiring channel knowledge and a method thereof are provided. At least one transmitter generates multiple directional beams in different directions, next modulates the directional beams in the different directions with at least one spreading sequence, so as to enlarge the beam range of each directional beam in the different directions and use the modulated directional beams as training-specific beams in the different directions, and sweeps the multiple training-specific beams in the different directions by using a plurality of antennas, so that at least one receiver measures at least one training-specific beam, and determines the channel knowledge according to the measurement result and beam-related information associated with the at least one training-specific beam, so as to achieve a technical effect of reducing training overhead.