LSTM mmWave Channel Estimation to Reduce Pilot Overhead
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Solution Overview
Problem
In millimeter-wave communication systems, the high propagation attenuation and the need for pilot signals proportional to the number of antennas in MIMO systems lead to increased pilot transmission overhead, which existing methods like least square and minimum mean square error methods fail to address effectively.
Innovation Solution
A channel estimation method using a long short-term memory network and a fully connected network to estimate channels from pilot signals received in time slots, extracting time-varying channel features and estimating parameters in a continuous domain, reducing pilot overhead by estimating in the time domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a MIMO system uses a plurality of antennas to offset high propagation attenuation in mmWave communication, then the communication reliability is improved, but the pilot transmission overhead increases proportionally with the number of antennas
Solution Approach 1:
The patent transforms the channel estimation problem from the frequency domain to the time domain by changing the parameter domain. Instead of estimating channel coefficients for each subcarrier independently in the frequency domain, the method uses a geometric channel model in the time domain where channel parameters (angles, delays, gains) are estimated once and applied across all subcarriers, thereby reducing pilot overhead while maintaining estimation accuracy
Solution Approach 2:
The patent uses a geometric channel model that copies the same spatial-temporal channel parameters across all subcarriers. By estimating the channel in the time domain using a small number of pilots and then copying these parameter estimates to all frequency subcarriers through inverse Fourier transform, the system reduces the number of required pilots from being proportional to the number of antennas to a much smaller fixed number
2Measurement precision
If existing channel estimation methods like least square or minimum mean square error are used in MIMO systems, then the channel estimation accuracy is improved, but pilot transmission overhead occurs because at least the same number of pilots as the number of channel coefficients must be transmitted
Solution Approach 1:
The patent changes the domain parameter from frequency to time by using a geometric channel model. Instead of estimating channel coefficients H[k] for each subcarrier k in the frequency domain, the method estimates time-domain channel parameters (arrival angles, departure angles, delays, and gains) that are then transformed to all subcarriers, reducing the number of parameters to be estimated and thus reducing pilot overhead
Solution Approach 2:
The patent introduces a geometric dimension to the channel model by representing the channel in terms of spatial parameters (angles of arrival and departure) and temporal parameters (delays) rather than just frequency-domain coefficients. This geometric channel model allows the channel to be described by a smaller set of physical parameters that can be extrapolated across the frequency spectrum
3Measurement precision
If channel parameters are estimated in the frequency domain for each subcarrier, then the channel estimation covers all subcarriers, but the pilot transmission overhead increases with the number of channel coefficients
Solution Approach 1:
The patent changes the estimation domain from frequency to time by using the geometric channel model. The channel impulse response h(τ) is estimated in the time domain using a small number of pilots, and then the frequency-domain channel response H[k] for all subcarriers is obtained through Fourier transform, achieving full subcarrier coverage with reduced pilot overhead
Solution Approach 2:
The geometric channel model serves multiple functions simultaneously: it models the physical propagation paths, enables time-domain parameter estimation with few pilots, and provides frequency-domain channel responses for all subcarriers through Fourier transform. This universal model eliminates the need for separate estimation for each subcarrier
Data Source
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AI summary
A device and a method for channel estimation using a short/long-term memory network in a mmWave communication system are disclosed. The disclosed channel estimation method comprises the operations of: inputting a received pilot signal of a time slot to a short/long-term memory network; estimating a channel change state by using, as an input, the received pilot signal of the time slot in the short/long-term memory network so as to extract a time-varying channel feature embedding vector; estimating a parameter of a channel model by using, as an input, the time-varying channel feature embedding vector in a fully connected network; and estimating a channel for the received pilot signal of the time slot by using the parameter of the channel model.