Hi, I am new about constant envelope OFDM. Anyone knows what is good and/or bad about this? Thanks -dvo _____________________________________ Do you know a company who employs DSP engineers? Is it already listed at http://dsprelated.com/employers.php ?

# CE-OFDM

Started by ●May 12, 2007

Reply by ●May 12, 20072007-05-12

On May 12, 5:36 am, "dvo" <ngd...@yahoo.com> wrote:> Hi, > I am new about constant envelope OFDM. Anyone knows what is good and/or > bad about this? > Thanks > -dvo >I guess the good is that it's constant envelope and has the advantages of OFDM. The "traditional" OFDM can have large peak-to-average ratio which makes the dynamic range larger than other modulation schemes. The bad is that the data rate will have to be lower compared to traditional OFDM. And complexity depends on the implementation. Julius

Reply by ●May 13, 20072007-05-13

>On May 12, 5:36 am, "dvo" <ngd...@yahoo.com> wrote: >> Hi, >> I am new about constant envelope OFDM. Anyone knows what is goodand/or>> bad about this? >> Thanks >> -dvo >> > >I guess the good is that it's constant envelope and has the >advantages of OFDM. The "traditional" OFDM can have large >peak-to-average ratio which makes the dynamic range larger >than other modulation schemes. > >The bad is that the data rate will have to be lower compared >to traditional OFDM. And complexity depends on the >implementation. > >Julius > >what is a typical bits/Hz for CE-OFDM compared to conventional OFDM? what about the channel? it seems to me that the ofdm modem now sees result of the transform of the real channel with FM demodulator. I doubt whether ofdm is optimal for such environment. Also would FM demod introduce any orthogonality problem for ofdm demod ? btw, if we do synch & equalization at FM demod, why should we do again for ofdm demod? furthermore it seems that the overall system gain is not as great as it sounds at a first glance. thanks. -dvo _____________________________________ Do you know a company who employs DSP engineers? Is it already listed at http://dsprelated.com/employers.php ?

Reply by ●May 13, 20072007-05-13

>On May 12, 5:36 am, "dvo" <ngd...@yahoo.com> wrote: >> Hi, >> I am new about constant envelope OFDM. Anyone knows what is goodand/or>> bad about this? >> Thanks >> -dvo >> > >I guess the good is that it's constant envelope and has the >advantages of OFDM. The "traditional" OFDM can have large >peak-to-average ratio which makes the dynamic range larger >than other modulation schemes. > >The bad is that the data rate will have to be lower compared >to traditional OFDM. And complexity depends on the >implementation. > >Julius > >what is a typical bits/Hz for CE-OFDM compared to conventional OFDM? what about the channel? it seems to me that the ofdm modem now sees result of the transform of the real channel with FM demodulator. I doubt whether ofdm is optimal for such environment. Also would FM demod introduce any orthogonality problem for ofdm demod ? btw, if we do synch & equalization at FM demod, why should we do again for ofdm demod? furthermore it seems that the overall system gain is not as great as it sounds at a first glance. thanks. -dvo _____________________________________ Do you know a company who employs DSP engineers? Is it already listed at http://dsprelated.com/employers.php ?

Reply by ●May 13, 20072007-05-13

On May 12, 10:55 pm, "dvo" <ngd...@yahoo.com> wrote:> > what is a typical bits/Hz for CE-OFDM compared to conventional OFDM? > what about the channel? it seems to me that the ofdm modem now sees result > of the transform of the real channel with FM demodulator. I doubt whether > ofdm is optimal for such environment. Also would FM demod introduce any > orthogonality problem for ofdm demod ? > btw, if we do synch & equalization at FM demod, why should we do again for > ofdm demod? > furthermore it seems that the overall system gain is not as great as it > sounds at a first glance. > thanks. > -dvo >dvo, all your questions are implementation-specific. Which implementation are you talking about? Do you have a reference or something? Julius

Reply by ●May 13, 20072007-05-13

On May 12, 10:55 pm, "dvo" <ngd...@yahoo.com> wrote:> > what is a typical bits/Hz for CE-OFDM compared to conventional OFDM? > what about the channel? it seems to me that the ofdm modem now sees result > of the transform of the real channel with FM demodulator. I doubt whether > ofdm is optimal for such environment. Also would FM demod introduce any > orthogonality problem for ofdm demod ? > btw, if we do synch & equalization at FM demod, why should we do again for > ofdm demod? > furthermore it seems that the overall system gain is not as great as it > sounds at a first glance. > thanks. > -dvo >dvo, all your questions are implementation-specific. Which implementation are you talking about? Do you have a reference or something? Julius

Reply by ●May 13, 20072007-05-13

On May 12, 10:55 pm, "dvo" <ngd...@yahoo.com> wrote:> > what is a typical bits/Hz for CE-OFDM compared to conventional OFDM? > what about the channel? it seems to me that the ofdm modem now sees result > of the transform of the real channel with FM demodulator. I doubt whether > ofdm is optimal for such environment. Also would FM demod introduce any > orthogonality problem for ofdm demod ? > btw, if we do synch & equalization at FM demod, why should we do again for > ofdm demod? > furthermore it seems that the overall system gain is not as great as it > sounds at a first glance. > thanks. > -dvo >dvo, all your questions are implementation-specific. Which implementation are you talking about? Do you have a reference or something? Julius

Reply by ●May 13, 20072007-05-13

On 13 May 2007 05:44:55 -0700, julius <juliusk@gmail.com> wrote:>On May 12, 10:55 pm, "dvo" <ngd...@yahoo.com> wrote: > >> >> what is a typical bits/Hz for CE-OFDM compared to conventional OFDM? >> what about the channel? it seems to me that the ofdm modem now sees result >> of the transform of the real channel with FM demodulator. I doubt whether >> ofdm is optimal for such environment. Also would FM demod introduce any >> orthogonality problem for ofdm demod ? >> btw, if we do synch & equalization at FM demod, why should we do again for >> ofdm demod? >> furthermore it seems that the overall system gain is not as great as it >> sounds at a first glance. >> thanks. >> -dvo >> > >dvo, all your questions are implementation-specific. >Which implementation are you talking about? Do you >have a reference or something? > >Juliusx2 I've never heard of CE-OFDM, so it's a bit hard to comment. A reference would be nice. Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org

Reply by ●May 13, 20072007-05-13

On May 13, 12:19 pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:> x2 > > I've never heard of CE-OFDM, so it's a bit hard to comment. A > reference would be nice. >Especially because by definition, OFDM cannot be constant- envelope unless there is only one tone! :-) Julius

Reply by ●May 13, 20072007-05-13

julius wrote:>>I've never heard of CE-OFDM, so it's a bit hard to comment. A >>reference would be nice. >> > Especially because by definition, OFDM cannot be constant- > envelope unless there is only one tone! :-)Not quite :-) Imagine an OFDM symbol as a member of the class of n-FSK sequences designed for demodulation in the frequency domain... VLV