Channel Estimation for 5G mmWave Beamforming
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Solution Overview
Problem
In the mmWave band, conventional channel estimation methods for hybrid beamforming in 5G communication systems are inaccurate, leading to poor performance in scheduling and beamforming due to high path loss and limited coverage of reference signals.
Innovation Solution
A method and apparatus for channel estimation in wireless communication systems using a base station and terminal, where the base station transmits a set of reference beams, and the terminal selects effective beams based on reception strength to estimate the channel and generate feedback signals, reducing overhead and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reference signal-based channel estimation is used in mmWave band, then the method is simple and compatible with LTE, but the coverage is limited and estimation accuracy is poor due to high path loss
Solution Approach 1:
The patent segments the channel estimation process into two distinct phases: beam management phase using reference beams for coarse channel information, and data transmission phase using precoded reference signals for fine channel estimation. This segmentation allows each phase to use optimized methods appropriate to its requirements, improving overall estimation accuracy while managing complexity through clear phase separation.
Solution Approach 2:
The patent performs preliminary beam management and coarse channel estimation before data transmission using reference beams. This preliminary action establishes the beam directions and provides initial channel information that enables more accurate subsequent channel estimation during data transmission, effectively preparing the system in advance to overcome mmWave path loss challenges.
2Reliability
If more RF chains are used to improve diversity and multiplexing gain, then performance gain is obtained, but cost and system complexity increase
Solution Approach 1:
The patent implements partial digital beamforming where only a subset of antenna elements are connected to digital RF chains, while other elements use analog beamforming. This partial action approach achieves sufficient diversity gain for reliable communication without requiring full digital beamforming across all antenna elements, thereby reducing hardware complexity and cost while maintaining acceptable reliability.
Solution Approach 2:
The patent applies different beamforming approaches to different parts of the antenna array: digital beamforming is applied locally to specific antenna elements where precise channel control is needed, while analog beamforming is used for other elements. This local quality differentiation allows the system to achieve diversity gain in critical areas without incurring the full complexity of complete digital beamforming.
3Length of stationary object
If beamforming is applied to overcome path loss, then transmission distance increases, but channel estimation becomes more difficult due to directional selectivity
Solution Approach 1:
The patent introduces reference beams as intermediary signals that carry coarse channel information before actual data transmission. These reference beams serve as mediators that enable the receiver to acquire initial channel knowledge, which then facilitates more accurate channel estimation during the subsequent data transmission phase, effectively bridging the gap between beamforming and precise channel measurement.
Solution Approach 2:
The patent performs preliminary channel information acquisition using reference beams transmitted in specific beam directions before actual data transmission. This preliminary action allows the receiver to prepare channel estimates and beam selection in advance, making the subsequent channel estimation during data transmission more accurate and less difficult despite the directional nature of beamforming.
Data Source
AI summary
The present disclosure relates to a 5G or a pre-5G communication system to be provided in order to support a higher data transmission rate than a beyond 4G communication system such as LTE. A method for estimating a channel, by a terminal, in a wireless communication system supporting beamforming using a plurality of antenna elements, which embodiments of the present disclosure provide, comprises: a step of receiving, from a base station, a set of reference beams including a plurality of reference beams; a step of selecting at least one effective beam from the plurality of reference beams included in the set of reference beams; a step of estimating a channel between the base station and the terminal on the basis of the selected effective beam; a step of generating channel information regarding the estimated channel; and a step of transmitting the generated channel information to the base station.