802.16 MAC

Hi,
I find that 802.16 MAC supports both TDD and FDD.
But, which is the best option ?
Any link/doc that talks in detail about these ?

Thx in advans,
Karthik Balaguru

On Jan 30, 4:52*pm, karthikbalaguru <karthikbalagur...@gmail.com>
wrote:
> Hi,
> I find that 802.16 MAC supports both TDD and FDD.
> But, which is the best option ?
> Any link/doc that talks in detail about these ?
>

Is it purely because some countries only allow either FDD or TDD,
while some allow only FDD ?

Thx in advans,
Karthik Balaguru

On Wed, 30 Jan 2008 08:22:35 -0800 (PST), karthikbalaguru
<(E-Mail Removed)> wrote:

>On Jan 30, 4:52*pm, karthikbalaguru <karthikbalagur...@gmail.com>
>wrote:
>> Hi,
>> I find that 802.16 MAC supports both TDD and FDD.
>> But, which is the best option ?
>> Any link/doc that talks in detail about these ?
>>
>
>Is it purely because some countries only allow either FDD or TDD,
>while some allow only FDD ?
>
>Thx in advans,
>Karthik Balaguru

Some operators own spectrum that is split for FDD, and some don't, so
having both available (at least in the standard) covers all bases.
Most equipment will be made to do one or the other, not both.



Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org

On Jan 30, 10:38 pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
> On Wed, 30 Jan 2008 08:22:35 -0800 (PST), karthikbalaguru
>
> <karthikbalagur...@gmail.com> wrote:
> >On Jan 30, 4:52 pm, karthikbalaguru <karthikbalagur...@gmail.com>
> >wrote:
> >> Hi,
> >> I find that 802.16 MAC supports both TDD and FDD.
> >> But, which is the best option ?
> >> Any link/doc that talks in detail about these ?
>
> >Is it purely because some countries only allow either FDD or TDD,
> >while some allow only FDD ?
>
> >Thx in advans,
> >Karthik Balaguru
>
> Some operators own spectrum that is split for FDD, and some don't, so
> having both available (at least in the standard) covers all bases.
> Most equipment will be made to do one or the other, not both.
>
> Eric Jacobsen
> Minister of Algorithms
> Abineau Communicationshttp://www.ericjacobsen.org

well, there was this question when linkskog of beceem visited india,
he delivered a seminar on wimax..there this question was as to why
preference is to TDD, why not FDD ?. well, there was this clear
answer, (i dont remember the reasoning now), TDD is most preferable
for MIMO and beamforming..dspexperts in this group..should let us
know..as to why MIMO and beamforming go well with TDD and not FDD??

particle (filter) reddy

On Jan 30, 10:38*pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
> On Wed, 30 Jan 2008 08:22:35 -0800 (PST), karthikbalaguru
>
> <karthikbalagur...@gmail.com> wrote:
> >On Jan 30, 4:52*pm, karthikbalaguru <karthikbalagur...@gmail.com>
> >wrote:
> >> Hi,
> >> I find that 802.16 MAC supports both TDD and FDD.
> >> But, which is the best option ?
> >> Any link/doc that talks in detail about these ?
>
> >Is it purely because some countries only allow either FDD or TDD,
> >while some allow only FDD ?
>
> >Thx in advans,
> >Karthik Balaguru
>
> Some operators own spectrum that is split for FDD, and some don't, so
> having both available (at least in the standard) covers all bases.
> Most equipment will be made to do one or the other, not both.
>

Interestingly, I came across a link that claims with proper guard band
implementation,
cohabitance of TDD and FDD is possible within same bands in
WiMAX .

Karthik Balaguru

On Jan 30, 11:39*pm, "PARTICLEREDDY (STRAYDOG)"
<particlere...@gmail.com> wrote:
> On Jan 30, 10:38 pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
>
>
>
>
>
> > On Wed, 30 Jan 2008 08:22:35 -0800 (PST), karthikbalaguru
>
> > <karthikbalagur...@gmail.com> wrote:
> > >On Jan 30, 4:52 pm, karthikbalaguru <karthikbalagur...@gmail.com>
> > >wrote:
> > >> Hi,
> > >> I find that 802.16 MAC supports both TDD and FDD.
> > >> But, which is the best option ?
> > >> Any link/doc that talks in detail about these ?
>
> > >Is it purely because some countries only allow either FDD or TDD,
> > >while some allow only FDD ?
>
> > >Thx in advans,
> > >Karthik Balaguru
>
> > Some operators own spectrum that is split for FDD, and some don't, so
> > having both available (at least in the standard) covers all bases.
> > Most equipment will be made to do one or the other, not both.
>
> > Eric Jacobsen
> > Minister of Algorithms
> > Abineau Communicationshttp://www.ericjacobsen.org
>
> well, there was this question when linkskog of beceem visited india,
> he delivered a seminar on wimax..there this question was as to why
> preference is to TDD, why not FDD ?. well, there was this clear
> answer, (i dont remember the reasoning now), TDD is most preferable
> for MIMO and beamforming..dspexperts in this group..should let us
> know..as to why MIMO and beamforming go well with TDD and not FDD??
>

This increases my curiosity to know more about the reason for
preference given
to TDD compared with FDD
Any ideas ?

Karthik Balaguru

On Jan 30, 11:39*pm, "PARTICLEREDDY (STRAYDOG)"
<particlere...@gmail.com> wrote:
> On Jan 30, 10:38 pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
>
>
>
>
>
> > On Wed, 30 Jan 2008 08:22:35 -0800 (PST), karthikbalaguru
>
> > <karthikbalagur...@gmail.com> wrote:
> > >On Jan 30, 4:52 pm, karthikbalaguru <karthikbalagur...@gmail.com>
> > >wrote:
> > >> Hi,
> > >> I find that 802.16 MAC supports both TDD and FDD.
> > >> But, which is the best option ?
> > >> Any link/doc that talks in detail about these ?
>
> > >Is it purely because some countries only allow either FDD or TDD,
> > >while some allow only FDD ?
>
> > >Thx in advans,
> > >Karthik Balaguru
>
> > Some operators own spectrum that is split for FDD, and some don't, so
> > having both available (at least in the standard) covers all bases.
> > Most equipment will be made to do one or the other, not both.
>
> > Eric Jacobsen
> > Minister of Algorithms
> > Abineau Communicationshttp://www.ericjacobsen.org
>
> well, there was this question when linkskog of beceem visited india,
> he delivered a seminar on wimax..there this question was as to why
> preference is to TDD, why not FDD ?. well, there was this clear
> answer, (i dont remember the reasoning now), TDD is most preferable
> for MIMO and beamforming..dspexperts in this group..should let us
> know..as to why MIMO and beamforming go well with TDD and not FDD??
>

From the internet, I got the below links that answer to few of our
queries.
http://www.moonblinkwifi.com/fddvstddwimax.cfm
http://www.wirelessnetdesignline.com...leID=170100162
and other links from internet.

Thx,
Karthik Balaguru

On Wed, 30 Jan 2008 10:39:22 -0800 (PST), "PARTICLEREDDY (STRAYDOG)"
<(E-Mail Removed)> wrote:

>On Jan 30, 10:38 pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
>> On Wed, 30 Jan 2008 08:22:35 -0800 (PST), karthikbalaguru
>>
>> <karthikbalagur...@gmail.com> wrote:
>> >On Jan 30, 4:52 pm, karthikbalaguru <karthikbalagur...@gmail.com>
>> >wrote:
>> >> Hi,
>> >> I find that 802.16 MAC supports both TDD and FDD.
>> >> But, which is the best option ?
>> >> Any link/doc that talks in detail about these ?
>>
>> >Is it purely because some countries only allow either FDD or TDD,
>> >while some allow only FDD ?
>>
>> >Thx in advans,
>> >Karthik Balaguru
>>
>> Some operators own spectrum that is split for FDD, and some don't, so
>> having both available (at least in the standard) covers all bases.
>> Most equipment will be made to do one or the other, not both.
>>
>> Eric Jacobsen
>> Minister of Algorithms
>> Abineau Communicationshttp://www.ericjacobsen.org
>
>well, there was this question when linkskog of beceem visited india,
>he delivered a seminar on wimax..there this question was as to why
>preference is to TDD, why not FDD ?. well, there was this clear
>answer, (i dont remember the reasoning now), TDD is most preferable
>for MIMO and beamforming..dspexperts in this group..should let us
>know..as to why MIMO and beamforming go well with TDD and not FDD??
>
>particle (filter) reddy

TDD is a little easier for adaptation because the channel estimated at
either receiver will also be the same channel at the receiver at the
other end of the link (ignoring interference). In other words, the
channel propagation is symmetric in TDD, while it is not in FDD.

So for things like subcarrier adaptation or beamforming this can be
helpful, but, often, the fact that interference is NOT symmetric can
screw that up.

And in FDD it just means that you have to transmit channel information
in a side channel for adapation. That takes up some bandwidth, but
is doable (and I don't know whether 16e accounts for that or not).

Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org

On Feb 1, 5:39 am, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
> On Wed, 30 Jan 2008 10:39:22 -0800 (PST), "PARTICLEREDDY (STRAYDOG)"
>
>
>
> <particlere...@gmail.com> wrote:
> >On Jan 30, 10:38 pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
> >> On Wed, 30 Jan 2008 08:22:35 -0800 (PST), karthikbalaguru
>
> >> <karthikbalagur...@gmail.com> wrote:
> >> >On Jan 30, 4:52 pm, karthikbalaguru <karthikbalagur...@gmail.com>
> >> >wrote:
> >> >> Hi,
> >> >> I find that 802.16 MAC supports both TDD and FDD.
> >> >> But, which is the best option ?
> >> >> Any link/doc that talks in detail about these ?
>
> >> >Is it purely because some countries only allow either FDD or TDD,
> >> >while some allow only FDD ?
>
> >> >Thx in advans,
> >> >Karthik Balaguru
>
> >> Some operators own spectrum that is split for FDD, and some don't, so
> >> having both available (at least in the standard) covers all bases.
> >> Most equipment will be made to do one or the other, not both.
>
> >> Eric Jacobsen
> >> Minister of Algorithms
> >> Abineau Communicationshttp://www.ericjacobsen.org
>
> >well, there was this question when linkskog of beceem visited india,
> >he delivered a seminar on wimax..there this question was as to why
> >preference is to TDD, why not FDD ?. well, there was this clear
> >answer, (i dont remember the reasoning now), TDD is most preferable
> >for MIMO and beamforming..dspexperts in this group..should let us
> >know..as to why MIMO and beamforming go well with TDD and not FDD??
>
> >particle (filter) reddy
>
> TDD is a little easier for adaptation because the channel estimated at
> either receiver will also be the same channel at the receiver at the
> other end of the link (ignoring interference). In other words, the
> channel propagation is symmetric in TDD, while it is not in FDD.
>
> So for things like subcarrier adaptation or beamforming this can be
> helpful, but, often, the fact that interference is NOT symmetric can
> screw that up.
>
> And in FDD it just means that you have to transmit channel information
> in a side channel for adapation. That takes up some bandwidth, but
> is doable (and I don't know whether 16e accounts for that or not).
>
> Eric Jacobsen
> Minister of Algorithms
> Abineau Communicationshttp://www.ericjacobsen.org

thanks eric,
one good reason i saw in your point

thanks again
particle (filter) reddy