Hi, i'm doing a project on OFDM and currently i'm just playing
around
and exploring with the HiperLan/2 demo that comes together with Simulink.
I noticed at OFDM transmission, pilots are inserted and these pilots
are single sample datas inserted regularly btwn the actual data. These
pilots are generated by a Pseudo-random binary generator block.
What is this block? What is the theory behind it? And why do we use
this block to generate the pilots?
Pseudo-random sequence and pilots in OFDM
Started by ●November 22, 2005
Reply by ●November 28, 20052005-11-28
Hello,
Pilot signals are inserted in between (or at the beginning) of data samples
to aid channel estimation, synchronization and equalization. Mostly these
procedures requires the computation of auto and cross correlations of the
pilot samples. As PN sequences have good auto/cross correlation properties,
they are the simplest choices for pilot sequences.
bye
Sameer On 11/23/05, vcteo <vcteo@vcte...> wrote:
>
> Hi, i'm doing a project on OFDM and currently i'm just playing around
> and exploring with the HiperLan/2 demo that comes together with Simulink.
>
> I noticed at OFDM transmission, pilots are inserted and these pilots
> are single sample datas inserted regularly btwn the actual data. These
> pilots are generated by a Pseudo-random binary generator block.
>
> What is this block? What is the theory behind it? And why do we use
> this block to generate the pilots?
Pilot signals are inserted in between (or at the beginning) of data samples
to aid channel estimation, synchronization and equalization. Mostly these
procedures requires the computation of auto and cross correlations of the
pilot samples. As PN sequences have good auto/cross correlation properties,
they are the simplest choices for pilot sequences.
bye
Sameer On 11/23/05, vcteo <vcteo@vcte...> wrote:
>
> Hi, i'm doing a project on OFDM and currently i'm just playing around
> and exploring with the HiperLan/2 demo that comes together with Simulink.
>
> I noticed at OFDM transmission, pilots are inserted and these pilots
> are single sample datas inserted regularly btwn the actual data. These
> pilots are generated by a Pseudo-random binary generator block.
>
> What is this block? What is the theory behind it? And why do we use
> this block to generate the pilots?
Reply by ●November 28, 20052005-11-28
Thx, regarding the PN sequence. They are only quasi-random bits generated by
an algorithm right?
So, if they are just bits of 1 or -1 what makes them possess such correlation properties? Is it the combination of the bits that create such properties?
"Sameer S.M" <sameerece@same...> wrote: Hello,
Pilot signals are inserted in between (or at the beginning) of data samples to aid channel estimation, synchronization and equalization. Mostly these procedures requires the computation of auto and cross correlations of the pilot samples. As PN sequences have good auto/cross correlation properties, they are the simplest choices for pilot sequences.
bye
Sameer On 11/23/05, vcteo <vcteo@vcte...> wrote: Hi, i'm doing a project on OFDM and currently i'm just playing around
and exploring with the HiperLan/2 demo that comes together with Simulink.
I noticed at OFDM transmission, pilots are inserted and these pilots
are single sample datas inserted regularly btwn the actual data. These
pilots are generated by a Pseudo-random binary generator block.
What is this block? What is the theory behind it? And why do we use
this block to generate the pilots?
So, if they are just bits of 1 or -1 what makes them possess such correlation properties? Is it the combination of the bits that create such properties?
"Sameer S.M" <sameerece@same...> wrote: Hello,
Pilot signals are inserted in between (or at the beginning) of data samples to aid channel estimation, synchronization and equalization. Mostly these procedures requires the computation of auto and cross correlations of the pilot samples. As PN sequences have good auto/cross correlation properties, they are the simplest choices for pilot sequences.
bye
Sameer On 11/23/05, vcteo <vcteo@vcte...> wrote: Hi, i'm doing a project on OFDM and currently i'm just playing around
and exploring with the HiperLan/2 demo that comes together with Simulink.
I noticed at OFDM transmission, pilots are inserted and these pilots
are single sample datas inserted regularly btwn the actual data. These
pilots are generated by a Pseudo-random binary generator block.
What is this block? What is the theory behind it? And why do we use
this block to generate the pilots?
Reply by ●November 30, 20052005-11-30
hai,
Ya...u r right...Some special combinations of 1's and -1's pocesses some
wonderful correlation properties...These sequences are called Maximal Length
(ML) sequences. There are some more variants like Gold codes, Kasami codes
etc that too pocess similar properties...
bye
sameer
On 11/28/05, Vincent Teo <vcteo@vcte...> wrote:
>
> Thx, regarding the PN sequence. They are only quasi-random bits generated
> by an algorithm right?
> So, if they are just bits of 1 or -1 what makes them possess such
> correlation properties? Is it the combination of the bits that create such
> properties?
>
> *"Sameer S.M" <sameerece@same...>* wrote:
>
> Hello,
> Pilot signals are inserted in between (or at the beginning) of data
> samples to aid channel estimation, synchronization and equalization. Mostly
> these procedures requires the computation of auto and cross correlations of
> the pilot samples. As PN sequences have good auto/cross correlation
> properties, they are the simplest choices for pilot sequences.
>
> bye
> Sameer > On 11/23/05, vcteo <vcteo@vcte...> wrote:
> >
> > Hi, i'm doing a project on OFDM and currently i'm just playing around
> > and exploring with the HiperLan/2 demo that comes together with
> > Simulink.
> >
> > I noticed at OFDM transmission, pilots are inserted and these pilots
> > are single sample datas inserted regularly btwn the actual data. These
> > pilots are generated by a Pseudo-random binary generator block.
> >
> > What is this block? What is the theory behind it? And why do we use
> > this block to generate the pilots?
Ya...u r right...Some special combinations of 1's and -1's pocesses some
wonderful correlation properties...These sequences are called Maximal Length
(ML) sequences. There are some more variants like Gold codes, Kasami codes
etc that too pocess similar properties...
bye
sameer
On 11/28/05, Vincent Teo <vcteo@vcte...> wrote:
>
> Thx, regarding the PN sequence. They are only quasi-random bits generated
> by an algorithm right?
> So, if they are just bits of 1 or -1 what makes them possess such
> correlation properties? Is it the combination of the bits that create such
> properties?
>
> *"Sameer S.M" <sameerece@same...>* wrote:
>
> Hello,
> Pilot signals are inserted in between (or at the beginning) of data
> samples to aid channel estimation, synchronization and equalization. Mostly
> these procedures requires the computation of auto and cross correlations of
> the pilot samples. As PN sequences have good auto/cross correlation
> properties, they are the simplest choices for pilot sequences.
>
> bye
> Sameer > On 11/23/05, vcteo <vcteo@vcte...> wrote:
> >
> > Hi, i'm doing a project on OFDM and currently i'm just playing around
> > and exploring with the HiperLan/2 demo that comes together with
> > Simulink.
> >
> > I noticed at OFDM transmission, pilots are inserted and these pilots
> > are single sample datas inserted regularly btwn the actual data. These
> > pilots are generated by a Pseudo-random binary generator block.
> >
> > What is this block? What is the theory behind it? And why do we use
> > this block to generate the pilots?