Therefore we may choose to build a simpler practical

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Unformatted text preview: developed in Section 4.2 can be easily generalized to the above communication system. Letting condition for no ISI is that the folded spectrum ½ Ò ½ ´µ ÀÌ ´ µÀ ´ µÀÊ ´ µ, the ´ µ, is constant for all frequencies, i.e., Ò Ì Ì (4.15) One method to achieve the Nyquist condition is to fix the receiving filter to be the matched filter, i.e., set ÀÊ ´ µ £ ÀÌ ´ µÀ £ ´ µ, and choose the transmission filter so that (4.15) is satisfied. This is the Nyquist pulse design method described in Section 4.2. The major disadvantage of this pulseshaping method is that it is in general difficult to construct the appropriate analog filters for ÀÌ ´ µ and ÀÊ ´ µ in practice. Moreover, we have to know the channel response À ´ µ in advance to construct the transmission and receiving filters. An alternative method is to fix the transmission filter4 and choose the receiving filter ÀÊ ´ µ to satisfy the condition in (4.15). As for the previous method, it is also difficult...
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