On Apr 1, 6:48*am, ckian...@gmail.com wrote:
> On Mar 31, 8:11*pm, Ubaid Abdullah <ubaidabdul...@gmail.com> wrote:
>
>
>
> > > Since PAPR should be
> > > computed before any matched filtering (am I right?), it seemed to
> > > imply that RC pulse is used at the transmitter pulse shaping and hence
> > > no matched filtering at the receiver.
>
> > I dont think so. PAPR is a parameter of importance for power
> > amplifier. That means we are interested in the PAPR of the final
> > waveform that comes out of your DAC. You will compute PAPR for the
> > signal that is input to the PA not at any other stage of the
> > transmitter.
>
> > Using RC pulse shaping at the transmitter doesn't imply that you
> > shouldn't use matched filtering at the receiver. You should perceive
> > matched filtering as a device that filters the out-of-band noise at
> > the receiver and applies weights to the samples. You always need
> > something for this job whatever the pulse shaping filter you use at
> > the transmitter.
>
> > Ubaid Abdullahhttp://dspdotcomm.blogspot.com
>
> I agree with you. But is there any reason to use a RC instead of RRC?
> What matched filter should one use to maintain ISI free and still
> filter the out-of-band noise?

You have two requirements for a communication system design.

i). Zero ISI
ii). Implementation of a matched filter at the receiver.

A raised cosine filter is one that is designed to produce zero ISI.
But, this zero ISI is needed before detection of the symbols or after
matched filtering. If you implement raised cosine filter at the
transmitter, the overall response of transmitting raised cosine filter
and matched filter doesn't produce zero ISI. That's why RC filter is
broken down into two parts each with an RRC response. In this case, we
will implement RRC filter at the transmitter and the same filter at
the receiver as matched filter to get the overall RC response. This
gives us zero ISI prior to detection and fulfills both the
requirements stated above.

Ubaid Abdullah
http://dspdotcomm.blogspot.com