In orthogonal frequency division multiplexing(OFDM) systems,time and frequency synchronization are two critical elements for guaranteeing the orthogonality of OFDM subcarriers.Conventionally,with the employment of pseudo-noise(PN) sequences in preamble design,the preamble information is not fully utilized in both symbol timing offset acquisition and carrier frequency offset estimation.In this article,a new synchronization algorithm is proposed for jointly optimizing the time and frequency synchronization.This algorithm uses polynomial sequences as synchronization preamble instead of PN sequences.Theoretical analysis and simulation results indicate that the proposed algorithm is much more accurate and reliable than other existing methods.
为克服串行RapidIO(Serial RapidIO,SRIO)互连系统中由于硬件实现的失误和恶劣环境造成的大量噪声与电磁干扰(Electromagnetic interference,EMI),提出了作为现有SRIO规范扩展的鲁棒传输协议(Robust trans portprotocol,ROTP)。ROTP用速率转换和模式转换提高SRIO性能。速率转换可提高恶劣环境下的系统平均吞吐量,模式转换可有效减少对反馈信道的使用。仿真与分析表明,ROTP方法可有效增强SRIO在恶劣环境下的鲁棒性,提高系统性能。
For multiple-relay cooperative networks with multiple antennas deployed at source and destination nodes,we investigate the outage performance of selection based semi-blind amplify-and-forward(AF) relaying,where transmit beamforming(TB) is conducted at source transmission and maximum ratio combining(MRC) at destination reception.Based on the Kolmogorov-Smirnov test,we analyze the impact of the configuration of destination antennas on the outage performance under arbitrary Nakagami-m fading channels.Results reveal that increasing the number of destination antennas is not necessary for an improvement of outage performance with any Nakagami-m parameter.Inspired by this fact,an approximation is proposed for the optimal selection.Simulation results show that the approximation is an efficient selection method.
In this paper we have investigated the performance of downlink generalized distributed antenna system(GDAS).Under the assumption of spatial correlated fading conditions,we have derived the numeric expression of correlated coefficients according to series of Bessel function,and have lifted the range restriction of the mean angle of incident.Moreover,the architecture of distributed generalized layered space time codes(GLST) has been considered in order to achieve both multiplexing gain and diversity gain while we have used basis vector from null space instead of orthogonal set to obtain the same system performance but with lower complexity.Furthermore,in order to maximize the capacity,Gerschgorin circles based fast antenna selection algorithms have been evaluated including a discussion of those simulation results.
