Channel delay estimation via pilot sub-carriers is used to provide accurate frame synchronization in multipath channels.
利用有限的导频信号进行信道延迟估计从而获得准确的符号同步。
But this method occupies the special sub-carriers or time slots and then reduces the system spectrum efficiency and data transmission rate.
但该方法占用专门的子载波或时隙，降低了系统的频谱利用率和信息传输速率。
The simulation results show that the bit swap algorithm rapidly and optimally reallocates the bits and power between sub-carriers for a time stationary power-line channel.
仿真分析表明，交换算法在平稳信道环境中，运算速度快且能够保证分配结果的最优性。
It copies the original data stream to several parallel data streams, spreads them in both time and frequency domain, then modulates them to orthogonal sub-carriers for transmission.
它先将原始数据流复制成多路并行数据，经频域扩频和时域扩频，再调制到互相正交的子载波上传输。
However in uplink channel, each user has its own frequency offset which leads to a loss of orthogonality among the sub-carriers and multiuser interference at the base station receiver.
在上行链路中每个用户由于载波频率偏差而存在潜在的不同步，这样使子载波之间失去正交性，从而在基站接收端产生多用户间干扰。
This is due to its use of the orthogonality between sub-carriers. This feature allows different sub-carrier signals overlapping in the spectrum without affecting their respective reception.
这得益于它利用了子载波之间的正交性，使得不同子载波信号在频谱上相互重叠，却不影响它们各自的接收。
When a synchronization error exists, the orthogonality between sub-carriers can't be maintained, serious inter-carrier interference is introduced and demodulation performance will be degraded greatly.
当存在同步错误时，子载波之间的正交性遭到破坏，从而引起严重的载波间干扰，使解调性能大大下降。
Purpose Nanoparticles, drug carriers in the sub-micron size range, can enhance the therapeutic efficacy of encapsulated drug by increasing and sustaining the delivery of the drug inside the cell.
药物以亚微粒大小被携带的纳米粒技术可以通过增加和延长药物在细胞内的释放来增强被包囊药物的治疗效果。
Sub-Saharan Africa remains the hardest hit, in 2007 the number of HIV carriers accounting for 67% of the world's AIDS deaths accounted for 72% of the world.
撒哈拉沙漠以南非洲地区仍是重灾区，2007年艾滋病病毒感染者数量占全球67％，艾滋病死亡人数占全球72％。
Sub-Saharan Africa remains the hardest hit, in 2007 the number of HIV carriers accounting for 67% of the world's AIDS deaths accounted for 72% of the world.
撒哈拉沙漠以南非洲地区仍是重灾区，2007年艾滋病病毒感染者数量占全球67％，艾滋病死亡人数占全球72％。
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