Younghwan Jin

Additional Diversity Gain in OFDM Receivers under the Influence of IQ Imbalances

In this paper, we analyze the effects of IQ (in-phase/ quadrature-phase) imbalances at both transmitter and receiver of OFDM (orthogonal frequency division multiplexing) system and show that more diversity gain can be achieved even though there are unwanted IQ imbalances. When mixed sub-carriers within an OFDM symbol due to the IQ imbalances undergo frequency selective channels, additional diversity effects are expected during the demodulation process. Simulation results on the symbol error rate (SER) performance with ML (maximum likelihood) and OSIC (ordered successive interference cancellation) receiver show that significant performance gain can be achieved with the diversity gain caused by the IQ imbalances combined with the frequency selective channels.

Obtained Diversity Gain in OFDM Systems under the Influence of IQ Imbalance

In this paper, we analyze the effects of IQ (In-phase/Quadrature-phase) imbalance at both transmitter and receiver of OFDM (Orthogonal Frequency Division Multiplexing) system and show that more diversity gain can be achieved even though there are unwanted IQ imbalance. When mixed sub-carriers within an OFDM symbol due to the IQ imbalance undergo frequency selective channels, additional diversity effects are expected during the demodulation process. Simulation results on the symbol error rate (SER) performance with ML (Maximum Likelihood) and OSIC (Ordered Successive Interference Cancellation) receiver show that significant performance gain can be achieved with the diversity gain caused by the IQ imbalance combined with the frequency selective channels.

Obtaining Diversity Gain Coming from IQ Imbalances in OFDM Receivers

In this paper, we analyze the effects of IQ (in-phase/quadrature-phase) imbalances at both transmitter and receiver of OFDM (orthogonal frequency division multiplexing) system and show that more diversity gain can be achieved even though there are unwanted IQ imbalances. When mixed sub-carriers within an OFDM symbol due to the IQ imbalances undergo frequency selective channels, additional diversity effects are expected during the demodulation process. Simulation results on the symbol error rate (SER) performance with ML (maximum likelihood) and OSIC (ordered successive interference cancellation) receiver show that significant performance gain can be achieved with the diversity gain caused by the IQ imbalances combined with the frequency selective channels.

Novel channel estimation method for coherent IR-UWB

A novel channel estimation scheme is proposed for coherent impulse radio ultra wideband (IR-UWB) system based on IEEE 802.15.4a specification. By extracting and utilizing the information on the frequency synchronization, the proposed channel estimation algorithm improves the receiver performance even under the restricted number of preamble symbols in IEEE 802.15.4a signal format. Simulation results over the IEEE 802.15.4a channel models show the performance gain with the proposed algorithm compared to ordinary channel estimation method.

Adaptive Timing Synchronization Algorithm for WiBro Uplink

An adaptive ranging technique for orthogonal frequency division multiple access (OFDMA) uplink transmission is proposed for timing synchronization of multiple mobile stations located at different distances from a base station. By combining the timing phase compensated frequency domain cross-correlation (TPCFDC) and frequency domain differential cross-correlation (FDDC), the proposed scheme reduces the number of correlators used in ordinary TPCFDC. Repeated initial ranging attempt with the FDDC in the proposed scheme greatly reduces the complexity of hardware implementation. Simulation results for ranging success probability and average ranging attempts count show that the proposed algorithm performs similarly with the ordinary TPCFDC even with the ten times reduced complexity