Zhuo Wu

An Interference Cancellation Scheme for Cognitive Radio Network

This paper investigates the interference cancellation for a cognitive radio based CDMA system, and the object is to reduce the interference both to the primary and the cognitive users. We propose a beamforming scheme in which the cognitive users operate in the licensed band without causing any interference to the primary user, while employing the interference cancellation technology at the receive side of the cognitive users to eliminate the passive effect from the primary user to the greatest extent. Simulation results show that the proposed scheme has a significant effect on removing the interference in a cognitive radio based CDMA system.

PIC Detector for Joint Distributed STBC under Imperfect Synchronization

In this paper, a new signal detection scheme using both parallel interference cancellation (PIC) and equalization for the efficient joint distributed space-time coding is proposed to suppress the impact of imperfect synchronisation in distributed cellular systems. Simulation results show that the proposed scheme outperforms the existing joint DSTBC decoded scheme in terms of BER. And also it achieves the same system capacity as the existing scheme. Meanwhile, a low structure and computational complexity has been retained.

An Efficient STBC Detection Algorithm Under Interference-Limited Environment

In this paper, we propose a detection and decoding scheme for a MIMO system using space-time codes (STBC) with external interferences. It is known that current cellular systems are limited by co-channel interference (CCI) more than thermal noise. However, traditional linear decoding schemes have rather poor performance in decoding STBC in this interference-limited environment. To achieve good BER performance with low complexity, an improved minimum mean square error (MMSE) multiuser detection (MUD) with partial group interference cancellation (IC) scheme has been proposed and used. We mainly focus on STBC detection with the one strongest interference and the top two strongest interferences models, which are the most realistic scenario under this circumstance. Finally we present some simulation results to show the advantage of our scheme.

Low complexity real-time power allocation algorithm to improve BER performance in cooperative communication systems

Cooperative diversity is a new technology to improve BER performance in wireless communication. A new power allocation algorithm to improve BER performance in cellular uplink has been proposed in this paper. The other power allocation schemes were for the purpose of maximizing the channel capacity or minimizing the outage probability. Different from these schemes, the proposed algorithm aims at minimizing BER of the systems under the constraint of total transmission power. Besides this characteristic, the proposed algorithm can realize a low complexity real-time power allocation according to the fluctuation of channels. The results of simulation show that the proposed algorithm can decrease BER of the systems effectively.

Design of a Novel Frequency Domain Equalizer for OFDM Systems

This paper proposes a novel frequency domain equalizer (FEQ) to eliminate inter-symbol interference (ISI) and inter-carrier interference (ICI) in orthogonal frequency division multiplexing (OFDM) systems. This FEQ employs the minimum mean square error (MMSE) criterion for getting an optimum FEQ structure based on minimizing interference. Simulation results show that the equalizer is capable of eliminating ISI and ICI effectively, and suppressing noise simultaneously.

SISO CDMA System Over Fading Channel

Based on both the flat fading and fast fading channels model, this paper analyses the performance of single-input-single-output (SISO) receiver in detail and simulation results shows channel coding contribute to the BER performance of SISO wireless communications system.