Jae-Shin Han

MIMO-OFDM Transceivers With Dual-Polarized Division Multiplexing and Diversity for Multimedia Broadcasting Services

This brief paper presents multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with dual-polarized division multiplexing (PDM) and diversity for multimedia broadcasting services. In particular, the polarized diversity is realized by transmitting two independent and distributed space-frequency coded signals through two sets of dual-polarized transmit antennas. In the corresponding polarized receptions, MIMO zero-forcing (ZF) detection and ZF detection combined with a group-wise or a symbol-wise successive cancelation (SIC) are used to minimize a depolarization effect caused by a cross-polarization discrimination (XPD). Furthermore, we analyze the output signal-to-interference-plus-noise ratio (SINR) of such MIMO detections in terms of the XPD effect. It is shown that the output SINR of MIMO ZF detection increases as the absolute XPD value increases. It is also shown that the output SINR of ZF-SIC detection converges to that of ZF detection as the absolute XPD value increases. Finally, we compare the performances of uni-polarized and dual-polarized MIMO-OFDM systems over a multipath Rician channel with XPD. From simulation results, we conclude that as the absolute XPD value increases, the polarized MIMO-OFDM systems provide a lower symbol error rate than uni-polarized MIMO-OFDM systems.

Cooperative Networks with Amplify-and-Forward Multiple-Full-Duplex Relays

In this paper, we present a cooperative system with amplify-and-forward (AF) multiple-full-duplex relays (FDRs) that receives and transmits signals simultaneously. In the first, we propose a new concept of delayed M-FDR relaying (M-D-FDR) scheme being able to achieve the full spatial diversity. At this time, we consider each delayed FDR receives a signal from source, adjacent relays and its delayed loop interference signal from its transmit antenna. In the second, we propose an efficient iterative successive interference cancellation (SIC) technique at destination that gradually cancels a delayed signal in order to fully obtain link diversity generated from M-D-FDR. Then, we investigate the various properties of the proposed M-D-FDR network by analyzing the pairwise-error-probability (PEP) analysis, especially in terms of signal-to-noise ratios (SNRs) between source to relays and source to destination links, respectively. Finally, we accomplish the performance evaluations to verify the analysis results and to compare with a non-delayed M-FDR (M-N-FDR) network.

Channel Estimations Using Extended Orthogonal Codes for AF Multiple-Relay Networks Over Frequency-Selective Fading Channels

In this paper, we present the efficient channel estimation scheme for amplify-and-forward (AF) multiple-relay networks in frequency-selective fading channels. It is first addressed that a known sequence transmitted from a source must have a perfect correlation property to achieve a minimum channel estimation error, particularly in the least squares (LS) sense. The known sequences retransmitted from the multiple relay must have to be decoupled at the destination to completely estimate the channel impulse responses (CIRs) between multiple links. To satisfy such requirements, we then propose a repeated known sequence consisting of Chu sequences at a source and a signed identity precoding using extended orthogonal codes, i.e., Hadamard codes, at relays. Moreover, we investigate various properties of the proposed channel estimations through the analysis of mean square error (MSE).

Formulating the Net Gain of SISO-SFN in the Presence of Erasure Effect

In this paper, an analytical formula for the net gain of single-input single-output single frequency network (SISO-SFN) is derived. In order to formulate the net SISO-SFN gain (SISO-SFNG), we derive the average signal to noise ratio, where the SFN gain is calculated by the aggregate power sum as a function of the power imbalance, whereas the SFN loss is calculated by a two-term exponential model from a curve fitting as a function of the erasure probability, modulation order, and code rate. The accuracy and effectiveness of the derived formula are verified by comparing the measurement results with the analytical results. The derived formula helps to rationalize why the net gain is positive or negative under a given condition, e.g., a negative net gain is obtained if the power imbalance exceeds the erasure-free limit. The formula would be very useful to predict more realistic and accurate service coverage of SISO-SFN for various system configurations.

MIMO Cloud Transmission Based on BICM-ID for High Data Rate Local Contents Delivery

A novel cloud transmission (CTxn) technique is proposed based on the multiple-input multiple-output (MIMO), called MIMO CTxn. Even though conventional single-input single-output (SISO) CTxn is operated at a negative signal-to-interference plus noise power ratio (SINR), where interference power is the same as the desired signal power, a critical drawback of SISO CTxn is that the maximum achievable spectral efficiency is less than 1 bit/s/Hz. Applying a MIMO technique to the conventional SISO CTxn provides a very efficient way to support high-date-rate service for delivering local contents, even at a negative SINR. Simulation results show that MIMO CTxn outperforms SISO CTxn while supporting high-order modulation and a high code rate. For instance, 16-QAM code rate 1/3 MIMO CTxn outperforms 4-QAM code rate 1/3 SISO CTxn from the SINR point of view. Further, the performance of MIMO CTxn is invariant with respect to the power imbalance and the difference between the received signal strengths. This makes the coverage planning much easy because all the other regions operate well without any loss of data rate if the coverage is planned with respect to the worst case.

Performance analysis of channel estimation in amplify-and-forward multi-hop direct forwarding wireless networks

In this paper, we study the performance of a training-based least square LS and linear minimum mean-square-error LMMSE channel estimation for both hop-by-hop and multi-hop direct forwarding wireless sensor networks over frequency-selective fading channels. Specifically, to investigate the properties of the channel estimation, we accomplish a theoretical analysis of MSE in terms of various link parameters. From the performance evaluation, we analytically present the effects of the number of hops on the MSE performance for channel estimations in both multi-hop networks. Interesting observations of MSE behaviors under various conditions are discussed, and the receiver complexity and channel equalization performance are also analyzed. Finally, through the computer simulations, the analytical results and detection performance are demonstrated. Copyright

Design of training sequences and channel estimation for amplify-and-forward two-path relaying networks

This paper proposes a new channel estimation scheme for two-path relaying networks where two amplify-and-forward (AF) half-duplex relay nodes alternatively transmit the signals received from a source node. The channel estimation and interference cancellation would be mutually conditional in two-path relaying networks. To overcome such a difficulty, we design new training sequences and propose precoding matrices for use at the source and relays. Deriving the Cramer-Rao lower bound (CRLB), it is shown that the proposed estimator is efficient, i.e., the proposed channel estimation scheme achieves the CRLB. The performance of the proposed channel estimation is evaluated through the computer simulations where the validity of the theoretical analysis is also demonstrated.

Cooperative space-time block coded full-duplex relaying over frequency-selective channel

In this study, the authors investigate a distributed time-reversal space-time block coded (D-TR-STBC) system with amplify-and-forward full duplex relaying (FDR) over frequency-selective channel. In the first, they present an FDR to use in a cooperative D-STBC relaying in which a relay transmits the delayed signal as much as one frame in order to maintain the orthogonal property of STBC at the destination. Then, they briefly present the conventional full self-interference cancellation (SIC) which continuously removes the self-interference signal. As an alternative to the full SIC, they further introduce a partial SIC that periodically performs the SIC process. As a result, it can reduce cancellation processing by a half time compared to the full SIC. In the second, they propose the efficient and yet optimal destination structure consisting of the forward interference cancellation (IC), backward IC and joint equalisation and data combining in order to obtain a full coding gain. It is shown that the proposed D-TR-STBC-FDR system has ∼3 dB signal-to-noise ratio gain compared to cooperative half-duplex relaying with D-TR-STBC while it has the same diversity order. In addition, they show that there are no performance losses between FDR with full SIC and FDR with partial SIC.

Full-duplex multiple relays: A high data rate cooperative communications over rayleigh fading channels

In this paper, we present a cooperative network with multi-node amplify-and-forward (AF) full-duplex relays (FDRs). In particular, we propose a new concept of transmission protocol to achieve the spatial diversity in a distributed fashion. Firstly, we propose delayed FDRs equipped with two transmit and receive antennas. Each relay delays a received signal, and transmits the delayed signal to the destination. Delayed FDR also receives signals from source, adjacent relays and the loop-back interference signal from its transmit antenna when loop-back channel impulse response is not accurate. Then, we analyze the pairwise-error-probability (PEP) analysis, especially in terms of signal-to-noise ratios (SNRs) between the source to relays and the source to destination links. Finally, we accomplish bit-error-rate (BER) the performance evaluations of the proposed system.

Numerical analysis on the net Gross MISO-SFNG in DVB-T2 system

In this study, a step-by-step analysis on the net Gross single-input single-output single frequency network gain (SISO-SFNG) is presented. The net gain is calculated by subtracting the net gain of a MISO-SFN from that of a multiple-input singleoutput (MISO)-SFN. In order to predict the service coverage of SFN accurately, it is required to calculate the corresponding SFN gain accurately in the receive signal overlapping area of the SFN. Analytical formulas are derived to calculate the net gains of SISO-SFN and MISO-SFN as a function of the signal amplitude and delay spread at each receive point of SFN. Validity of the derived formulas is confirmed by comparing the numerical analysis results with the measurement data in the related studies. Finally, we exemplify a practical application of the derived formula to predict the net gain of MISO-SFN system by using the reference network with a reference planning configuration.