# US 10,313,172 B2 · System and method for enhanced channel estimation using tap-dependent frequency offset (FO) estimation

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- Number: US 10,313,172 B2
- Document ID: US10313172B2
- Status: Granted
- Kind: B2
- Application number: 15/883,790
- Filed: 2018-01-30
- Published: 2018-06-21
- Granted: 2019-06-04
- Earliest claimed: 2016-03-07
- Assignees: Samsung Electronics Co., Ltd.
- Applicants: Samsung Electronics Co., Ltd.
- Inventors: Binnan Zhuang; Jung Hyun Bae; Dongwoon Bai; Jungwon Lee
- Web page: https://patentgrep.com/patent/US10313172B2

## CPC

- H04L 27/2662: {Symbol synchronisation}
- H04L 7/0058: {detection of error based on equalizer tap values}
- H04L 25/022: {of frequency response}
- H04L 25/025: {using least-mean-square [LMS] method}
- H04L 25/0256: {Channel estimation using minimum mean square error criteria}
- H04L 27/2657: {Carrier synchronisation}
- H04L 27/2695: {with channel estimation, e.g. determination of delay spread, derivative or peak tracking (channel estimation H04L25/0202)}
- H04L 7/033: using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
- H04L 2027/0055: {single phase}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A user equipment (UE) for channel estimation in a high-speed single-frequency network (HS-SFN) is provided. The UE includes at least one non-transitory computer-readable medium; and at least one processor, which, when executing instructions stored on the at least one non-transitory computer-readable medium, causes the UE to perform a method including calculating an estimated frequency offset (FO) correction for a received signal using at least an FO estimation generated by an automatic frequency control (AFC) module using at least a previously-calculated channel estimate output from a channel estimator (CE) as input in a first feedback loop; and calculating, by the CE, a current channel estimate using at least the received signal adjusted by the estimated FO correction from the first feedback loop and one or more channel parameter estimates generated by the AFC using at least the previously-calculated channel estimate output from the CE as input in a second feedback loop.

## Claims

### Claim 1

A user equipment (UE) capable of channel estimation in a high-speed single-frequency network (HS-SFN), comprising
at least one non-transitory computer-readable medium; and
at least one processor, which, when executing instructions stored on the at least one non-transitory computer-readable medium, causes the UE to perform a method comprising:
calculating an estimated frequency offset (FO) correction for a received signal using at least an FO estimation generated by an automatic frequency control (AFC) module using at least a previously-calculated channel estimate output from a channel estimator (CE) as input in a first feedback loop; and
calculating, by the CE, a current channel estimate using at least the received signal adjusted by the estimated FO correction from the first feedback loop and one or more channel parameter estimates generated by the AFC using at least the previously-calculated channel estimate output from the CE as input in a second feedback loop.

### Claim 2 (depends on 1)

The UE of claim 1, wherein the one or more channel parameter estimates comprise a per-tap frequency offset estimation for each tap in each orthogonal frequency division multiplexing (OFDM) symbol.

### Claim 3 (depends on 2)

The UE of claim 2, wherein calculating the current channel estimate comprises:
calculating interpolation coefficients to interpolate frequency domain (FD) channel values using the per-tap frequency offset estimations.

### Claim 4 (depends on 1)

The UE of claim 1, wherein the one or more channel parameter estimates comprise (i) a per-tap frequency offset estimation for each tap in each orthogonal frequency division multiplexing (OFDM) symbol, (ii) a per-tap channel power estimate, (iii) a per-tap delay estimate, and (iv) a noise variance estimate.

### Claim 5 (depends on 4)

The UE of claim 4, wherein calculating the current channel estimate comprises:
calculating minimum mean square error (MMSE) estimations using at least channel parameter estimates (i) through (iv).

### Claim 6 (depends on 5)

The UE of claim 5, wherein the method performed by the UE further comprises:
obtaining a raw channel impulse response (CIR) of the received signal.

### Claim 7 (depends on 6)

The UE of claim 6, wherein calculating the current channel estimate further comprises:
calculating MMSE combining weights for each tap using at least the four channel parameter estimates (i) through (iv); and
performing MMSE combining using the raw CIR and the MMSE combining weights.

### Claim 8 (depends on 5)

The UE of claim 5, wherein the method performed by the UE further comprises:
obtaining a raw frequency domain (FD) channel of the received signal.

### Claim 9 (depends on 8)

The UE of claim 8, wherein calculating the current channel estimate further comprises:
calculating MMSE combining weights for each subcarrier using at least channel parameter estimates (i) through (iv); and
performing MMSE combining for each subcarrier using the raw FD channels and the MMSE combining weights.

### Claim 10 (depends on 8)

The UE of claim 8, wherein calculating the current channel estimate further comprises:
calculating MMSE combining weights and performing MMSE combining on subsampled subcarriers using at least channel parameter estimates (i) through (iv) and the raw FD channels; and
approximating an estimated FD channel based at least on the MMSE combining using MMSE combining weights calculated based on subsampled subcarriers.