A mobile phone forum. Mobile-Forum

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » Mobile-Forum forum » General mobile phone forums » GSM
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Single chipset supports all major cellular standards



 
 
Thread Tools Display Modes
  #31  
Old September 29th 03, 08:07 PM
external usenet poster
 
Posts: n/a
Default

On Sat, 27 Sep 2003 22:31:31 GMT, "N9WOS"
wrote:

The computers can handle that.
That is the point of a dynamic system.
The computers can allocate space and
channels on a real time basses as the loading occurs.
There is no need for planning. :-)


Hmmmmmmmmm.........
That gives me an idea for a network forecast.
Something that you could get from the 611 menu.

......................................
Welcome to the N9 dynamic cellular network.
Current network weather for the day of September 27.

12.5 megahertz currently in use.
2.5 megahertz currently available.
5 megahertz unallocated.

Operating spectrum is as follows.
3 CDMA carriers.
152 TDMA carriers
33 GSM carriers
8 analog carriers.

There has been 3 unsuccessful calls and
21 dropped calls within the last hour.

To go back to the main menu, hit 1,
Or hit end to finish the call at any time.


Good thought!

................................................. ....
Kinda makes me think of the solar forecast on WWV. :-)


The Boulder K Index at 03 UT was 2....

  #32  
Old September 30th 03, 01:59 AM
matt weber
external usenet poster
 
Posts: n/a
Default

On Mon, 29 Sep 2003 00:57:21 GMT, "N9WOS"
wrote:


So how much guard band are we talking about?
1.2500 - 1.2288 = 0.0212 MHz or 21.2 KHz

That's the gap between two IS-95 CSMA carriers edges. Not enough for
one AMPS channel (30 KHz, three ID-136 timeslots) or one GSM channel
(200 KHz, eight timeslots). Between a band edge and a carrier edge
would be half that, 10.6 KHz.

There isn't enough room, unless we're willing to accept some
interference.


The spreading sequence and data correction should tolerate
some fringe signals without loss of data.
And it will just show up as white noise to the TDMA carrier.
And it will be so much lower than the signal level
of the TDMA carrier that the TDMA carrier won't notice.

Technically, a CDMA signal should be able to tolerate a
narrow band signal or two within it's pasband without any problem.
Remember the whole ruckus in the ham community about
sharing ham bands with spread spectrum modes.

Having two tdma signals right in the middle of the 1.2meg pas band
should only raise the noise floor for the CDMA channel a few DB
and the tdma signals won't even notice a DB raise in noise floor.
CDMA gets that off it's military heritage.
It is it's one true distinct capability.
But that capability is never utilized with the cellular application.


The answer is that isn't quite that simple. Todays CDMA activities are
very toleratant of sharing space and rising noise floor , because the
chipping to data rate provides a processing gain on the order of 1000.
In other words a narrow interefering signal can only damage a tiny
portion of the data, because the data is spread so widely.

However when you go broad band applications that people are proposing
for use with
WCDMA, and instead of 10,000 bit per second channel, you want a 2
million bit per second channel, the gain from the chipping to data
rate is suddenly more like 2-3, and at that ratio, the system is a
whole lot less tolerant of raising the noise floor.
  #33  
Old September 30th 03, 04:22 AM
N9WOS
external usenet poster
 
Posts: n/a
Default

The answer is that isn't quite that simple. Todays CDMA activities are
very toleratant of sharing space and rising noise floor , because the
chipping to data rate provides a processing gain on the order of 1000.
In other words a narrow interefering signal can only damage a tiny
portion of the data, because the data is spread so widely.

However when you go broad band applications that people are proposing
for use with
WCDMA, and instead of 10,000 bit per second channel, you want a 2
million bit per second channel, the gain from the chipping to data
rate is suddenly more like 2-3, and at that ratio, the system is a
whole lot less tolerant of raising the noise floor.


The bandwidth verses power is the primary factor.

A 10kbps signal is still 20Khz of actual bandwidth
no matter how much the CDMA spreading process spreads it.

A 100mw 10Kbps CDMA signal has the same range as
A 100mw 10kbps 20Khz wide signal.

If you take a 1Mbps (2Mhz wide) signal and spread it across 5Mhz of
spectrum.
You will need a lot higher power to spread across the larger 2Mhz
bandwidth.
If you use TDMA, you can cut the TX time down to around 1/1000 of a
second at a rate of around 10 times a second.
For a total TX time of 1/100 of a second.
Of course, the peak TX power during that time will be around 10W. :-)
But you will still have 100mw average.
Granted, it wouldn't be hand held friendly.

During low usage, one phone could pretty much
use the entire 1Mbps channel.
Who needs 3G? :-)

You could stack a couple carriers on the band
with the chipping sequence rotated a few notches.

And since the signal is still Spread spectrum like CDMA,
you can use rake receivers to add reflected signals
and signals from multiple towers.


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
COM: Oxygen Phone Manager II v2.1.5 supports MMS messages Oxygen Software GSM 0 July 10th 03 03:44 PM


All times are GMT +1. The time now is 03:56 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2004-2018 Mobile-Forum.
The comments are property of their posters.