Delay Spread and Power Delay profile


Fourier Transform of Power Delay Profile is called spaced-frequency correlation function, which describes the spreading of a signal in frequency domain.This also give rise to the importance channel parameter - Coherence Bandwidth.

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Spread Spectrum Clock Generation (SSCG)

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Spread-spectrum clock generation (SSCG) is used in some  synchronous digital system   to reduce the spectral density of the  electromagnetic interference (EMI).   Jitter will cause transmitted bit error Because the generated clock will have variation between 5 GHz ~ 4.97 GHz, thus in the time domain , the clock waveform will have time variation. If the variation is too much, then the received waveform will have certain error because of clock timing variation which can be founded in the following figure :
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SIFS/DIFS/PIFS (802.11 Mac Layer)

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1.What is Short Inter-frame Space (SIFS)? Ans : the small time interval between the data frame and its acknowledgment . Used for the highest priority transmissions enabling stations with this type of information to access the radio link first. 2. What is the content of SIFS ? Ans :This value is fixed per PHY and is calculated in such a way that transmitting station will be able to switch back to receive mode and be capable of decoding the incoming packets. A SIFS duration is a constant value and it depends on the amendments . 3.What is  DCF inter-frame space( DIFS) ? Ans : The DIFS is used by stations operating under the DCF method to transmit data frames and management.(Read more : DCF Method ) 4.How to use DIFS? Ans : A station using the DCF is allowed to transmit if it determines that the medium is idle for the duration of the DIFS, or if it determines that the medium is idle for the duration of the DIFS + the remaining back-off time following the recept...
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