Narrowband Channel Estimation for Millimeter Wave Beam Alignment
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Solution Overview
Problem
Current wireless communication systems, particularly those using millimeter wave technology, face challenges in efficiently aligning beams for optimal signal transmission due to the directional nature of beamforming, leading to potential low antenna gain and high block error rates if the beam is not properly aligned with the user equipment (UE).
Innovation Solution
The system employs a method where the base station transmits beam reference signals (BRS) in various directions, allowing the UE to perform narrowband channel estimation and select the best beam, and subsequently, the UE feeds back this information to the base station. This process includes the use of beam refinement reference signals (BRRS) to further optimize beam alignment, enabling the base station to adjust and refine the beam selection for improved signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If beamforming is used to support wider coverage in millimeter wave communication, then coverage area is improved, but beam alignment precision deteriorates leading to low antenna gain and high block error rates
Solution Approach 1:
The beam reference signal is divided into multiple narrowband frequency subbands. The UE performs channel estimation separately on each subband to identify frequency-selective fading regions, then excludes these regions from CQI calculation. This segmentation approach allows the system to maintain wide beam coverage while achieving precise beam alignment by operating only on reliable frequency subbands.
2Measurement precision
If narrowband channel estimation is performed on beam reference signals, then beam alignment precision is improved, but frequency selectivity measurement complexity increases
Solution Approach 1:
The patent extracts only the necessary information from the narrowband channel estimation results. Instead of processing all frequency subbands equally, the system identifies and extracts only the subbands experiencing frequency-selective fading, then excludes them from further CQI calculation. This extraction approach reduces measurement complexity by focusing only on critical frequency regions rather than processing the entire bandwidth uniformly.
3Ease of manufacture
If CQI is calculated using wideband channel estimation, then calculation simplicity is improved, but frequency selectivity effects are lost leading to inaccurate CQI values
Solution Approach 1:
The patent performs preliminary narrowband channel estimation on individual frequency subbands before calculating the final CQI value. This preliminary action identifies which subbands are affected by frequency-selective fading, allowing the system to exclude them from the CQI calculation. This preliminary frequency subband analysis maintains relative calculation simplicity while significantly improving CQI accuracy by accounting for frequency selectivity effects.
Data Source
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AI summary
When beamforming (e.g., via a millimeter wave system (mmW)) is used for wireless communication, a base station may transmit beams that are directed to certain directions. Due to the directional nature of the beams in the mmW system, an approach to determine a beam that provides a desirable gain is studied. The apparatus may be a user equipment (UE). The apparatus receives, from a base station, a plurality of signals through a plurality of beams of the base station, each of the plurality of beams corresponding to a respective antenna port of a plurality of antenna ports of the base station. The apparatus receives from the base station a number of beams whose information should be fed back to the base station. The apparatus performs channel estimation for each beam of the plurality of beams from the plurality of antenna ports based on the plurality of signals.