generated symbol 中文意思是什麼
generated symbol
解釋
生成符號-
We detailed toeplitz operator with unomodular symbol, and generated the theorem proved by michael sand in [ 2 ] from h to h + c ( t ). in the second part of this paper, the author discussed simply when multipliction of two toeplitz operators with symbol in h + c ( t ) or in l. we got two conclusions by analyzing symbol of toeplitz operators. the last, we investigated whether multiplication of two toeplitz operators, which range included all non - cyclic vectors of backward shift, is surjective, and partly answered the question about surjective toeplitz algebra posed by michael sand in [ 2 ]
對于單個的toeplitz運算元，考慮其符號的內外分解，得到了它的滿射只與其幺模部分有關的結論，詳細地討論了符號為幺摸函數的toeplitz運算元的各種情況，在討論符號在h ~的特殊情形時，推廣michaelsand [ 2 ]中的定理2到h ~ + c （ t ） ，第二部分簡單地討論了符號在h ~ + c （ t ）以及l ~中的兩個toeplitz運算元的乘積的滿射情況，先對toeplitz運算元的符號進行分析得到兩個結論，最後考察了toeplitz運算元的乘積的值域包含后移運算元的所有非循環向量的滿射情況，部分地回答了michaelsand在[ 2 ]中提出的toeplitz代數滿射問題。 -
Firstly, in wireless environment, receiver has no know the time delay between transmitter and itself. in ofdm system, ofdm data is transmitted as one symbol, so in order for correct demodulation, the correct start of symbol should be got from ofdm system to reduce the effect of isi. secondly, the high frequency utilization in ofdm is based on the orthogonal properties of sub carriers. if frequency offset is generated, the orthogonal properties among sub carriers will lost, that will cause inter carrier interference ( ici ) and high ber of system
Ofdm技術也存在著一些缺陷，首先，在無線環境中傳輸的ofdm信號對定時要求高，為了減少碼間串擾（ isi ）影響，必須從接收信號中提取出正確的符號起始位;其次， ofdm系統對頻率偏移敏感， ofdm技術的高頻譜利用率和傳輸可靠性均以子載波的正交性為基礎，如果接收機和發射機之間發生頻率偏移，子載波之間就會失去正交性，導致嚴重的子載波間干擾（ ici ） ，降低系統性能。
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