santosh nath wrote:
> 
> 
>        ... I meant total software
> solution for time synchronization algorithm only. Since he has given a
> good solution with PLL , unfortunately I can not use that since it
> needs extra HW Ckt.   ...

Not necessarily. There are software PLLs. Google for "Costas loop". e.g.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

eric.jacobsen@ieee.org (Eric Jacobsen) wrote in message news:<3f22bced.47734556@news.earthlink.net>...
> Santosh,
> 
> You're aiming at a total software solution for 802.11a?   Is your
> intent to actually implement a real-time usable system this way?
> 
> I think you're going to have trouble meeting the SIFS timing
> requirement for turnaround to generate an ACK on a received packet.  I
> don't think anybody makes processors fast enough to do that in
> software.  A lot of people have trouble meeting timing with hardware
> solutions.
> 
> Cheers,
> 
> Eric


Sorry Eric, I did not clarify Vladimir's post. I meant total software
solution for time synchronization algorithm only. Since he has given a
good solution with PLL , unfortunately I can not use that since it
needs extra HW Ckt. As you know, Cox  et al gave nice solution on time
synchonization with ML correlator which is indeed a total software
solution.What I am missing in all these paper is a selection of a
proper buffer size/ or burst size(Mind it it is variable) without
which frame boundary detection would be difficult. At least my 
experience with GSM/EDGE equalization say so.I thought I could have
mentioned that we will indeed go for a total hardware solution of the
system  at the very end - a flow like simulink( with MATLAB or C S
functions)->VHDL->Optimization->FPGA->ASIC tap out.

I guess I understand processor load etc and have some knowledge on the
specification of the processors around us.

I have posted an earlier mail specific to get attention of you.

Hope I have clarified it better to get help from you.

Regards,
Santosh
   
> 
> 
> On 25 Jul 2003 04:39:39 -0700, santosh.nath@ntlworld.com (santosh
> nath) wrote:
> 
> >Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F209773.B4327435@abvolt.com>...
> >> You don't have to buffer the whole burst and search for the proper
> >> synchronization. Use a conventional early-late algorithm and the PLL. 
> >
> >Are you also talking about programable synthesized PLL with the
> >following components:
> >
> >R divder,N diverder with A & B programable pre-scalar,Phase
> >Detector,Loop filter and VCO.
> >
> >We are aiming at total software solution, probably PLL requires extra
> >HW ckt. Could you see how it could be done with correlator.  All
> >popular papers in IEEE uses the correlation with  ML estimation. -
> >unfortunately I found them to mention total number of samples like
> >1000000 as a simulation parameter but nobody mention about buffering
> >or detect burst by burst which could have been much easier to deal the
> >problem. Can anybody  ref. a paper?
> >santosh
> >
> >> 
> >> Vladimir Vassilevsky, Ph.D.
> >> 
> >> DSP and Mixed Signal Design Consultant
> >> 
> >> http://www.abvolt.com
> >> 
> >> 
> >> santosh nath wrote:
> >> > 
> >> > Hi all,
> >> > 
> >> > As we know the burst size is defined in GSM/EDGE mobile system as
> >> > 156.25 symbols
> >> > which takes 577 micro secs. This helps us to update our "Equalizer"
> >> > burst by burst. The symbol synchronization is done per burst
> >> > basis-meaning we calculate the time of arrival of a burst correlating
> >> > known training sequence with received samples.After calculating the
> >> > actual time offset we adjust start of a burst and then subsequent
> >> > other processes are carried forward.
> >> > 
> >> > As 802.11a specifies that burst size for a OFDM based PHY burst is of
> >> > variable
> >> > size. Say, It starts with 10 short OFDM preambles,2 long OFDM
> >> > preambles,1 Signal OFDM symbol and payload OFDM data symbols of
> >> > variable length .We use both short symbols and long symbols for robust
> >> > double correlation based timing sychronization.
> >> > 
> >> > Now I am wondering if we donot know the burst size in advance(since it
> >> > is variable)  how to get burst by burst  samples in the routine to
> >> > carry out time sychronization. A solution could be to use a buffer
> >> > size of (what length?).
> >> > 
> >> > Now how can we search(using known short preamble) through the buffer
> >> > to identify  for peaks ?  If the buffer is too big the complexity will
> >> > be very high.
> >> > 
> >> > So what should be the optimum buffer size?  or any other way to carry
> >> > out time synchronization from continuous stream(I thought it could be
> >> > difficult!!).
> >> > 
> >> > I googled without luck. I know there are guys who can answer it
> >> > instantly- that's why it is my fabourite group.
> >> > 
> >> > Regards,
> >> > Santosh
> 
> Eric Jacobsen
> Minister of Algorithms, Intel Corp.
> My opinions may not be Intel's opinions.
> http://www.ericjacobsen.org

santosh.nath@ntlworld.com (santosh nath) wrote in message news:<6afd943a.0307250339.1e805aa2@posting.google.com>...
> Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F209773.B4327435@abvolt.com>...
> > You don't have to buffer the whole burst and search for the proper
> > synchronization. Use a conventional early-late algorithm and the PLL. 
> 
> Are you also talking about programable synthesized PLL with the
> following components:
> 
> R divder,N diverder with A & B programable pre-scalar,Phase
> Detector,Loop filter and VCO.
> 
> We are aiming at total software solution, probably PLL requires extra
> HW ckt. Could you see how it could be done with correlator.  All
> popular papers in IEEE uses the correlation with  ML estimation. -
> unfortunately I found them to mention total number of samples like
> 1000000 as a simulation parameter but nobody mention about buffering
> or detect burst by burst which could have been much easier to deal the
> problem. Can anybody  ref. a paper?
> santosh
> 
> > 
> > Vladimir Vassilevsky, Ph.D.
> > 
> > DSP and Mixed Signal Design Consultant
> > 
> > http://www.abvolt.com
> > 
> > 
> > santosh nath wrote:
> > > 
> > > Hi all,
> > > 
> > > As we know the burst size is defined in GSM/EDGE mobile system as
> > > 156.25 symbols
> > > which takes 577 micro secs. This helps us to update our "Equalizer"
> > > burst by burst. The symbol synchronization is done per burst
> > > basis-meaning we calculate the time of arrival of a burst correlating
> > > known training sequence with received samples.After calculating the
> > > actual time offset we adjust start of a burst and then subsequent
> > > other processes are carried forward.
> > > 
> > > As 802.11a specifies that burst size for a OFDM based PHY burst is of
> > > variable
> > > size. Say, It starts with 10 short OFDM preambles,2 long OFDM
> > > preambles,1 Signal OFDM symbol and payload OFDM data symbols of
> > > variable length .We use both short symbols and long symbols for robust
> > > double correlation based timing sychronization.
> > > 
> > > Now I am wondering if we donot know the burst size in advance(since it
> > > is variable)  how to get burst by burst  samples in the routine to
> > > carry out time sychronization. A solution could be to use a buffer
> > > size of (what length?).
> > > 
> > > Now how can we search(using known short preamble) through the buffer
> > > to identify  for peaks ?  If the buffer is too big the complexity will
> > > be very high.
> > > 
> > > So what should be the optimum buffer size?  or any other way to carry
> > > out time synchronization from continuous stream(I thought it could be
> > > difficult!!).
> > > 
> > > I googled without luck. I know there are guys who can answer it
> > > instantly- that's why it is my fabourite group.
> > > 
> > > Regards,
> > > Santosh


I am re-sending the post - thinking somebody has missed it!
I guess "minister of algorithm" has something to comment on this.
I have enjoyed his thoughtful posts on communication-couple of being
in OFDM. J Kusuma writes also in this area - My question is bit
implementation specific to real hardware and real application. If
somebody comes up with a solution I will appriciate it very much.

Regards,
Santosh

Santosh,

You're aiming at a total software solution for 802.11a?   Is your
intent to actually implement a real-time usable system this way?

I think you're going to have trouble meeting the SIFS timing
requirement for turnaround to generate an ACK on a received packet.  I
don't think anybody makes processors fast enough to do that in
software.  A lot of people have trouble meeting timing with hardware
solutions.

Cheers,

Eric


On 25 Jul 2003 04:39:39 -0700, santosh.nath@ntlworld.com (santosh
nath) wrote:

>Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F209773.B4327435@abvolt.com>...
>> You don't have to buffer the whole burst and search for the proper
>> synchronization. Use a conventional early-late algorithm and the PLL. 
>
>Are you also talking about programable synthesized PLL with the
>following components:
>
>R divder,N diverder with A & B programable pre-scalar,Phase
>Detector,Loop filter and VCO.
>
>We are aiming at total software solution, probably PLL requires extra
>HW ckt. Could you see how it could be done with correlator.  All
>popular papers in IEEE uses the correlation with  ML estimation. -
>unfortunately I found them to mention total number of samples like
>1000000 as a simulation parameter but nobody mention about buffering
>or detect burst by burst which could have been much easier to deal the
>problem. Can anybody  ref. a paper?
>santosh
>
>> 
>> Vladimir Vassilevsky, Ph.D.
>> 
>> DSP and Mixed Signal Design Consultant
>> 
>> http://www.abvolt.com
>> 
>> 
>> santosh nath wrote:
>> > 
>> > Hi all,
>> > 
>> > As we know the burst size is defined in GSM/EDGE mobile system as
>> > 156.25 symbols
>> > which takes 577 micro secs. This helps us to update our "Equalizer"
>> > burst by burst. The symbol synchronization is done per burst
>> > basis-meaning we calculate the time of arrival of a burst correlating
>> > known training sequence with received samples.After calculating the
>> > actual time offset we adjust start of a burst and then subsequent
>> > other processes are carried forward.
>> > 
>> > As 802.11a specifies that burst size for a OFDM based PHY burst is of
>> > variable
>> > size. Say, It starts with 10 short OFDM preambles,2 long OFDM
>> > preambles,1 Signal OFDM symbol and payload OFDM data symbols of
>> > variable length .We use both short symbols and long symbols for robust
>> > double correlation based timing sychronization.
>> > 
>> > Now I am wondering if we donot know the burst size in advance(since it
>> > is variable)  how to get burst by burst  samples in the routine to
>> > carry out time sychronization. A solution could be to use a buffer
>> > size of (what length?).
>> > 
>> > Now how can we search(using known short preamble) through the buffer
>> > to identify  for peaks ?  If the buffer is too big the complexity will
>> > be very high.
>> > 
>> > So what should be the optimum buffer size?  or any other way to carry
>> > out time synchronization from continuous stream(I thought it could be
>> > difficult!!).
>> > 
>> > I googled without luck. I know there are guys who can answer it
>> > instantly- that's why it is my fabourite group.
>> > 
>> > Regards,
>> > Santosh

Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org

Vladimir Vassilevsky <vlv@abvolt.com> wrote in message news:<3F209773.B4327435@abvolt.com>...
> You don't have to buffer the whole burst and search for the proper
> synchronization. Use a conventional early-late algorithm and the PLL. 

Are you also talking about programable synthesized PLL with the
following components:

R divder,N diverder with A & B programable pre-scalar,Phase
Detector,Loop filter and VCO.

We are aiming at total software solution, probably PLL requires extra
HW ckt. Could you see how it could be done with correlator.  All
popular papers in IEEE uses the correlation with  ML estimation. -
unfortunately I found them to mention total number of samples like
1000000 as a simulation parameter but nobody mention about buffering
or detect burst by burst which could have been much easier to deal the
problem. Can anybody  ref. a paper?
santosh

> 
> Vladimir Vassilevsky, Ph.D.
> 
> DSP and Mixed Signal Design Consultant
> 
> http://www.abvolt.com
> 
> 
> santosh nath wrote:
> > 
> > Hi all,
> > 
> > As we know the burst size is defined in GSM/EDGE mobile system as
> > 156.25 symbols
> > which takes 577 micro secs. This helps us to update our "Equalizer"
> > burst by burst. The symbol synchronization is done per burst
> > basis-meaning we calculate the time of arrival of a burst correlating
> > known training sequence with received samples.After calculating the
> > actual time offset we adjust start of a burst and then subsequent
> > other processes are carried forward.
> > 
> > As 802.11a specifies that burst size for a OFDM based PHY burst is of
> > variable
> > size. Say, It starts with 10 short OFDM preambles,2 long OFDM
> > preambles,1 Signal OFDM symbol and payload OFDM data symbols of
> > variable length .We use both short symbols and long symbols for robust
> > double correlation based timing sychronization.
> > 
> > Now I am wondering if we donot know the burst size in advance(since it
> > is variable)  how to get burst by burst  samples in the routine to
> > carry out time sychronization. A solution could be to use a buffer
> > size of (what length?).
> > 
> > Now how can we search(using known short preamble) through the buffer
> > to identify  for peaks ?  If the buffer is too big the complexity will
> > be very high.
> > 
> > So what should be the optimum buffer size?  or any other way to carry
> > out time synchronization from continuous stream(I thought it could be
> > difficult!!).
> > 
> > I googled without luck. I know there are guys who can answer it
> > instantly- that's why it is my fabourite group.
> > 
> > Regards,
> > Santosh

You don't have to buffer the whole burst and search for the proper
synchronization. Use a conventional early-late algorithm and the PLL. 

Vladimir Vassilevsky, Ph.D.

DSP and Mixed Signal Design Consultant

http://www.abvolt.com


santosh nath wrote:
> 
> Hi all,
> 
> As we know the burst size is defined in GSM/EDGE mobile system as
> 156.25 symbols
> which takes 577 micro secs. This helps us to update our "Equalizer"
> burst by burst. The symbol synchronization is done per burst
> basis-meaning we calculate the time of arrival of a burst correlating
> known training sequence with received samples.After calculating the
> actual time offset we adjust start of a burst and then subsequent
> other processes are carried forward.
> 
> As 802.11a specifies that burst size for a OFDM based PHY burst is of
> variable
> size. Say, It starts with 10 short OFDM preambles,2 long OFDM
> preambles,1 Signal OFDM symbol and payload OFDM data symbols of
> variable length .We use both short symbols and long symbols for robust
> double correlation based timing sychronization.
> 
> Now I am wondering if we donot know the burst size in advance(since it
> is variable)  how to get burst by burst  samples in the routine to
> carry out time sychronization. A solution could be to use a buffer
> size of (what length?).
> 
> Now how can we search(using known short preamble) through the buffer
> to identify  for peaks ?  If the buffer is too big the complexity will
> be very high.
> 
> So what should be the optimum buffer size?  or any other way to carry
> out time synchronization from continuous stream(I thought it could be
> difficult!!).
> 
> I googled without luck. I know there are guys who can answer it
> instantly- that's why it is my fabourite group.
> 
> Regards,
> Santosh

Hi all,

As we know the burst size is defined in GSM/EDGE mobile system as
156.25 symbols
which takes 577 micro secs. This helps us to update our "Equalizer"
burst by burst. The symbol synchronization is done per burst
basis-meaning we calculate the time of arrival of a burst correlating
known training sequence with received samples.After calculating the
actual time offset we adjust start of a burst and then subsequent
other processes are carried forward.

As 802.11a specifies that burst size for a OFDM based PHY burst is of
variable
size. Say, It starts with 10 short OFDM preambles,2 long OFDM
preambles,1 Signal OFDM symbol and payload OFDM data symbols of
variable length .We use both short symbols and long symbols for robust
double correlation based timing sychronization.

Now I am wondering if we donot know the burst size in advance(since it
is variable)  how to get burst by burst  samples in the routine to
carry out time sychronization. A solution could be to use a buffer
size of (what length?).

Now how can we search(using known short preamble) through the buffer
to identify  for peaks ?  If the buffer is too big the complexity will
be very high.

So what should be the optimum buffer size?  or any other way to carry
out time synchronization from continuous stream(I thought it could be
difficult!!).

I googled without luck. I know there are guys who can answer it
instantly- that's why it is my fabourite group.

Regards,
Santosh