The Eight time slots

[Ext User(tomar)]

Hi all,
If the frequency is considered to a scarce resource then, please
clarify why
they have choosen 8 TS structure why not 16 or 32 also for GSM900 the
frequency bands are 890-915 MHz and 935-960 MHz. Then, why the
frquency bandwidth of 20 Mhz was left out in specifications. The 20
Mhz here iam referring here is 915-935 Mhz. Note: the duplex distance
of 45 Mhz can still be maintained.

[Ext User(Derek)]

"tomar" <manojkumartomar@gmail.com> wrote in message
news:1186205660.851022.114380@x40g2000prg.googlegr oups.com...
> Hi all,
> If the frequency is considered to a scarce resource then, please
> clarify why they have choosen 8 TS structure why not 16 or 32
That would result in lower voice quality.

> frquency bandwidth of 20 Mhz was left out in specifications. The 20
> Mhz here iam referring here is 915-935 Mhz. Note: the duplex distance
> of 45 Mhz can still be maintained.
>
This is FULL duplex not half duplex, meaning the transmitter and receiver
are running at the same time.
No one has yet designed a duplexer http://en.wikipedia.org/wiki/Duplexer
which could do what you suggest.

[Ext User(tomar)]

Derek sir, please explain how the speech quality will be be degraded
if they have choosen 16 time slot structure for the TDMA frame. My
arguement is that it is the speech codec which will be representing my
voice(analog to pcm and then speech coding). Now once i have this
particular stream of bits from a speech codec plus various protections
added to these bits, i have to send this information to BTS by using
GMSK . But 8 TS per TDMA frame will allow me to send my information
after every 4.6ms(TDMA frame length)........What was the problem with
them if i have to send my information after 4.6x2=9.2msecs. Is the
delay of 9.2 ms is not acceptable in human ear behaviour or something
else................and if they have gone for a duplex distance of
40mhz instead of 45 then is there any limitations. like the advantage
was that we can have more carriers by using the unutilized spectrum
from 915-935mhz.

[Ext User(who where)]

On Sun, 05 Aug 2007 08:10:00 -0000, tomar <manojkumartomar@gmail.com> wrote:

>Derek sir, please explain how the speech quality will be be degraded
>if they have choosen 16 time slot structure for the TDMA frame. My
>arguement is that it is the speech codec which will be representing my
>voice(analog to pcm and then speech coding). Now once i have this
>particular stream of bits from a speech codec plus various protections
>added to these bits, i have to send this information to BTS by using
>GMSK . But 8 TS per TDMA frame will allow me to send my information
>after every 4.6ms(TDMA frame length)........What was the problem with
>them if i have to send my information after 4.6x2=9.2msecs. Is the
>delay of 9.2 ms is not acceptable in human ear behaviour or something
>else

I think you have missed the point of 8-vs-16 timeslots (or I have).

it's not the latency that is the issue, it is the need to get your realtime
analog speech into one of 16 slots every frame, not one of 8. Either you
require MORE bits per slot (which means more bandwidth required, defeating the
purpose of 16 slots in lieu of 8) or you have a poorer quality encoded signal.

There is no such thing as a free lunch. You squeeze 16 signals into the space
previously supporting eight users, and the quality will go down.

[Ext User(tomar)]

For REAL TIME SPEECH, if they can hold(buffer) the speech for 4.6ms
then why can't they hold it for 9.2 msec.
and please give reply justified by FACTS.