Shao Huaizong

Broadband Robust Adaptive Beamforming in the Presence of Correlated interferences and DOA uncertainties

A novel method of broadband robust adaptive beamforming is proposed in this paper to deal with the signal cancellation caused by correlated interferences and DOA uncertainties. To achieve this goal, the classic techniques of spectral averaging and diagonal loading are integrated into the beamforming, with the former aiming at decorrelation and the latter at robustness against DOA uncertainties. Moreover, the optimal loading is selected based on worst-case performance optimization and a simple closed-form solution to it is suggested after some approximations. Besides its simplicity and low computational cost, this analytical solution reveals how different factors affect the optimal loading. Compared with many relevant methods, the proposed one achieves better robustness against DOA uncertainties, while suppressing both correlated and uncorrelated interferences effectively. Its excellent performance is confirmed via a number of numerical examples.

Adaptive bit and power loading algorithm with low complexity in MIMO-OFDM systems

Two adaptive power and bit loading algorithms to maximize the throughput of MIMO-OFDM systems in frequency selective fading environment are proposed. The two algorithms allocate bit based on maximizing the overall throughput. One algorithm allocates power based on guaranteeing that the bit error rate (BER) of each sub-carrier and the total allocated power remain below a target BER threshold and a power threshold, respectively; another one allocates power based on guaranteeing that the mean BER of sub-carriers and the total allocated power remain below a target BER threshold and a power threshold, respectively. The simulation results show that the proposed algorithms can achieve faster throughput with lower computational complexity, which indicates that the proposed algorithms are effective when compared to some existing algorithms.

The Application of High-Rate LDPC Codes in Image Transmission over Wireless Channel

It has been proved that low-density parity-check (LDPC) codes is good codes and have good distance. They have near Shannon limit performance when decoded using an iterative probabilistic algorithm. Moreover, high-rate LDPC codes have high data rate and high spectral efficiency. So, in this paper, we explored three high-rate LDPC codes in image transmission over Rayleigh fading channel, the simulation results show that high rate LDPC codes can obtain high information speed and bandwidth efficiency, they also can achieve high reliability and excellent performance in image communication over wireless channels. We also found that the performance is more sensitive to code rate than to code length

Study of adaptive modulation and LDPC coding in multicarrier systems

Abstract An adaptive modulation (AM) algorithm is proposed and the application of the adapting algorithm together with low-density parity-check (LDPC) codes in multicarrier systems is investigated. The AM algorithm is based on minimizing the average bit error rate (BER) of systems, the combination of AM algorithm and LDPC codes with different code rates (half and three-fourths) are studied. The proposed AM algorithm with that of Fischer et al is compared. Simulation results show that the performance of the proposed AM algorithm is better than that of the Fischers algorithm. The results also show that application of the proposed AM algorithm together with LDPC codes can greatly improve the performance of multicarrier systems. Results also show that the performance of the proposed algorithm is degraded with an increase in code rate when code length is the same.

Image Transmission with High-Rate LDPC Codes in Multicarrier Systems

Low-density parity-check (LDPC) codes have near Shannon performance and easy to implement, multicarrier modulation can achieve high spectral efficiency and resist the inter-symbol interference (ISI). In this paper, we explored three high rate LDPC codes in image transmission with multicarrier modulation. The simulation results show that the combination of multicarrier modulation and high rate LDPC codes can obtain high information speed and high bandwidth efficiency with high reliability and excellent performance in image communication over wireless channels. This can solve the problems about transmission speed and efficiency caused by large quantity of image data. We also found that the performance is more sensitive to code rate than to code length