Browsing by Author "Sun, Ming-Fu"

Now showing 1 - 4 of 4

A 62.8 mW 4x4 MIMO-OFDM Modem with One-Symbol-Locked Timing Recovery, Frequency-Dependent I/Q Mismatch Estimation and Adaptive Equalization
(2009)
Sun, Ming-Fu
;
Lin, You-Hsien
;
Lai, Wei-Chi
;
Juan, Ta-Yang
;
Lee, Cheng-Yuan
A 4x4 multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDM) modem with one-symbol-locked timing recovery, anti-I/Q mismatch frequency recovery, frequency-dependent I/Q mismatch estimation and adaptive equalization is implemented in 0.13-mu m CMOS library. This chip occupies 4.6x4.6 mm(2) and consumes 62.8 mW at 1.2 V.
Adaptive Frequency-Domain Channel Estimator in 4 x 4 MIMO-OFDM Modems
(2009-11-01)
Sun, Ming-Fu
;
Juan, Ta-Yang
;
Lin, Kan-Si
;
Hsu, Terng-Yin
;
資訊工程學系
This work presents an adaptive frequency-domain channel estimator (FD-CE) for equalization of space-time block code multiple-input multiple-output ( MIMO) orthogonal frequency-division multiplexing (OFDM) systems in time-varying frequency-selective fading. The proposed adaptive FD-CE ensures the channel estimation accuracy in each set of four MIMO-OFDM symbols. Performance evaluation shows that the proposed method achieved a 10% packet error rate of 64 quadrature amplitude modulation (QAM) at 29.5 dB SNR under 120 km/h ( Doppler shift is 266 Hz) in 4 4 MIMO-OFDM systems. To decrease complexity, the rich feature of Alamouti-like matrix is exploited to derive an efficient very large-scale integration (VLSI) solution. Finally, this adaptive FD-CE using an in-house 0.13-m CMOS library occupies an area of 3 X 3.1 mm(2), and the 4 X 4 MIMO-OFDM modem consumes about 62.8 mW at 1.2 V supply voltage.
Estimation of carrier frequency offset with I/Q mismatch using pseudo offset injection in OFDM systems
(2008-04-01)
Sun, Ming-Fu
;
Yu, Jui-Yuan
;
Hsu, Temg-Yin
;
資訊工程學系
;
Department of Computer Science
This work presents a novel carrier frequency offset (CFO) estimation algorithm, based on pseudo-CFO (P-CFO), to estimate the CFO value under the conditions of I/Q mismatch for direct conversion structures with 2-dB gain error and 20-deg. phase error in frequency selective fading channels. To circumvent CFO with I/Q mismatch, the proposed P-CFO algorithm rotates three training symbols by adding extra frequency offset into the received sequence to improve CFO estimation. Simulation results indicate that the estimation error of the proposed method is about 0.3 ppm, which is lower than those of two-repeat preamble-based methods. Additionally, the proposed P-CFO algorithm is compatible with the conventional method, and is appropriate for SoC implementation. The proposed scheme is implemented as part of an orthogonal frequency-division multiplexing wireless receiver fabricated in a 0.13-mu m CMOS process with 3.3 x 0.4 mm(2) core area and 10-mW power consumption at 54-Mbits/s data rate.
Preamble-Assisted Estimation for Frequency-Dependent I/Q Mismatch in Direct-Conversion OFDM Receivers
(2009-07-01)
Sun, Ming-Fu
;
Hsu, Terng-Yin
;
資訊工程學系
;
Department of Computer Science
In direct-conversion orthogonal frequency division multiplexing (OFDM) receivers, the impact of frequency-dependent I/Q mismatch (IQ-M) with carrier frequency offset (CFO) must be considered. A preamble-assisted estimation is developed to circumvent the frequency-dependent IQ-M with CFO. The results of a simulation and an experiment show that the proposed method could provide good estimation efficiency and enhance the system performance. Moreover, the proposed scheme is compatible with current wireless local area network standards.