LDPC based differential unitary space-frequency coding for MIMO-OFDM systems

INTRODUCTION Unitary space-time modulation (USTM) (Hochwald and Marzetta, 2000) has been shown to be ideally suited for Rayleigh flat fading channels when there is no CSI. And for continuously changing fading channels, differential unitary space-time modulation (DUSTM) was proposed in Hochwald and Sweldens (2000). However, the performance of DUSTM de-grades considerably in frequency-selective fading channels often encountered in broadband wireless communications. Hence concatena…     

钾盐,植物生长调节剂和青霉素对小麦生理及产量的影响

以一定浓度的ＮＡＡ、６－ＢＡ、ＫＣＩ,ＫＨ２ＰＯ４和青霉素浓液,对扬花期小麦进行大田喷施。,经测定发现,处理后不同时期小麦旗叶的蒸腾速率,叶绿素含量和硝酸还原酶活力高于对照组。结果表明,在小麦生长发育的一定时期合理施用某些化学药剂,可调节和促进生理活性并对增产起积极作用。