The frequency-offset estimation of a wireless asynchronous transfer mode (ATM) modem based on the orthogonal frequency division multiplexing (OFDM) is discussed. For burst synchronization operating under the time-division multiple access (TDMA) medium access control (MAC), an OFDM preamble using a multistage frequency-offset estimation technique is proposed and shown to have a good accuracy with a large estimation range. And also an averaged decision-directed channel estimation (ADDCE) technique suitable for burst data is proposed.

In this letter, we focus on achieving the reconfiguration of a multi-rate interference cancellation (IC) scheme via a software radio implementation. In the proposed multi-rate IC scheme, the estimates of each user signal are updated every cancellation stage with more clean signal, which are used in the next stage to yield more reliable estimates.

As dual-polarized multiple-input multiple-output (MIMO) technique has little inter-antenna interference, it provides high data rate and reliability to a user equipment (UE) with the low system complexity. In the joint transmission (JT) technique of the coordinated multi-point (CoMP) transmission system, multiple transmission points (TPs) transmit the same data to the UE so that the UE can get the diversity gain and the high reliability, especially at the cell-edge. However, the system performance of the dual-polarized MIMO in the JT technique of CoMP system is very sensitive on the dual-polarized channel state when the channel is asymmetric. In this letter, an improved dual-polarized MIMO scheme for JT of the downlink CoMP transmission system is proposed. This scheme adaptively applies the transmission power to each dual-polarized MIMO antenna and the modulation order of the transmission data according to the channel state information (CSI). System-level simulation results show that the proposed scheme provides better bit-error-rate (BER) performance in the asymmetric dual-polarized channel state than the conventional scheme.

In this letter, we present a coarse frequency-offset synchronization technique for Eureka-147 DAB receiver. The proposed frequency-offset synchronization algorithm using two defined correlation functions is shown to have high robustness against a large range of symbol timing offset with a moderate implementational complexity.

In this letter, we address the performance evaluation of a space-time block coded (STBC) orthogonal frequency and code division multiplexing (OFCDM) system encountered with time-variant channels. For the performance evaluation, the average bit error rate (BER) impairment due to imperfect channel information is investigated taking into account the effect of time-varying channels. Derived results show that the loss of orthogonality due to the time variation of the channel incurs the channel estimation error, which causes performance degradation.

This letter is concerned with a new algorithm which can be used to design a time-domain equalizer (TEQ) for xDSL systems employing the discrete multitone (DMT) modulation. The proposed algorithm, derived by neglecting the terms which do not affect the performance of a DMT system in ARMA modeling, is shown to have a good performance compared with the previous TEQ algorithms even with a significantly lower computational complexity. In addition, the proposed algorithm does not require the channel impulse response or training sequence, since all processing is made only with the received data.

This letter addresses the edge effect on a windowed discrete Fourier transform (WDFT)-based channel estimator for orthogonal frequency division multiplexing (OFDM) systems with virtual carriers in non-sample spaced channels and derives a sufficient condition to reduce the edge effect. Moreover, a modified WDFT-based channel estimator with multi-step linear prediction as an edge effect reduction technique is proposed. Simulation results show that it offers around 5 dB signal-to-noise ratio (SNR) gain over the conventional WDFT-based channel estimator at bit error rate (BER) of 10-3.

This letter deals with our investigations into improving the performance of a wireless uplink system when an orthogonal frequency-division multiple access (OFDMA) is used as an access scheme. To do this, the OFDMA-based uplink system adopts a frequency diversity coupled with a cyclic time shift (CTS) at the transmitter, which is named as the FD-OFDMA system with CTS. It is found that the multi-user FD-OFDMA system equipping with CTS can decrease the probability of destroying the orthogonality among the users and provide the MAI-robust reception without decreasing the bandwidth efficiency of the system.

In this paper, we propose a new digital duplexing scheme, called synchronous digital duplexing (SDD), which can increase data efficiency and flexibility of resource by transmitting uplink signal and downlink signal simultaneously in wireless communication. In order to transmit uplink and downlink signals simultaneously, the proposed SDD obtains mutual information among subscriber stations (SSs) with a mutual ranging symbol. This information is used for selection of transmission time, decision on cyclic suffix (CS) insertion, determination of CS length, and re-establishment of FFT starting point.

This letter describes two adaptive timing synchronization schemes for a short-ranged Bluetooth system in the partial-band noise environments. One estimates the variance of the partial-band interference, which is utilized for the trigger threshold value of the inquiry scan and page scan states, while second is designed using the scaled partial correlation value for the connection state. Numerical results show the proposed synchronization algorithms are robust to the partial-band noise interference and of low complexity, which is suitable for a low-cost personal area network (PAN).

This letter is concerned with a channel estimation technique with interference cancellation in a wireless personal area network (WPAN) system with complementary code keying (CCK) signaling. The performance of the coherent detector based on the proposed channel estimation scheme is compared with that of a noncoherent detector, and a significant improvement of performance is observed due to the self-interference cancellation.

This letter presents a channel estimation and a DC-offset estimation technique in a short-ranged Bluetooth system. Each of the Bluetooth devices in the connection state knows the access codes used in the ad-hoc networks, which is utilized as a reference signal for the parameter estimation. The proposed estimators can be implemented without degradation of frame and spectral efficiency thanks to using the access code specified for the Bluetooth system.