Subject: [NEXTEL-1] Re: another interference case

From: [email-masked]
Date: Tue, 04 Nov 2003 11:01:24 -0500

-------- Original Message --------
From: "eric995us" <[email-masked]>
Subject: Re: another interference case

--- In [email-masked], <eric.h.lawson@a...> wrote:
> I'm 10 minutes **late*** late for a  9:00 meeting....but, Dave, 
rest easy...I don't think it is a Nextel problem.  
>  
>  
> A quick thought though.... do different companies have different 
levels of responsibility for fixing dead spots around their sites?
> Eric

I'm finally back.  My dad has been in the hospital.  Heart failure... 
They got that under control, and then he got dehydrated and ended up 
back in the hospital for the dehydration.  They tweaked the 
medication dosages and it looks like he is getting better very 
quickly.

To brag on my dad a bit...The local USMC outfit had their Birthday 
celebration a bit early as they are expecting to be overseas on the 
10th.  He was well enough to go and, at 90 years old, he was the 
oldest Marine there.  It was really neat seeing him up there at the 
cake--looking embarassed as they read off the    l o n g   (and 
impressive) list of decorations that he had received over his 30 year 
career.  

Anyway.  Enough of that.

The problem that I've been working on is due to the strong signal 
from an "on the street" police department radio site and not from one 
of the cell sites as was originally suggested. 

(climbing into the the flame proof coveralls... :-) 
Do all the things that everyone says about the commerical low height 
sites apply to public safety low height sites too?  

Eric

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---

From: [email-masked]
Date: Tue, 04 Nov 2003 15:30:15 -0500

-------- Original Message --------
   From: "Ron Haraseth" <[email-masked]>
Subject:  Re: another interference case

 Frankly, the PS vs. PS interference scenario you mention is a rare bird
in current systems.This has been addressed in the Consensus Plan.  There
are definitions of "cellular like" implementation that consider the
number of users (load) and the height and power of a fixed station and
what part of the band in which they can operate.  Expectations for both
sides of the issue, what level of signal is regarded as a "best
practice" for incumbent target systems that may receive  interference.
(Don't expect too much interference protection if you are depending on a
signal level of -110 dBm in the an area experiencing interference etc.
should have designed better coverage to start with.)  The actual
protection levels listed in Appendix F are -98 and -95 dBm depending on
whether the station receiving interference is an old system or a new
system (post rebanding).  Any user, public safety included, that would
meet the criteria for "cellular like" system topology would have to
abide by the same rules as a commercial/business provider.In a post
"re-banding" world, it would be significantly easier to recognize,
identify, and work through any remaining interference issues with more
compatible systems.  For one thing, public safety systems are pretty
static, they don't dynamically move the frequencies around the system as
load demands change during the day or as they split and re-configure
cells etc.  Fix it once when noticed, not every Monday as it
changes.Ron-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Tuesday, November 04, 2003 1:11 PM
Subject: Re: another interference case
 It is a "food for thought" question where I'm playing the devil's
advocate...which is why I said I was putting on my flameproof
coveralls! It seems that everyone beats up on the commercial low site
operators when a reception problem occurs nearby a commercial low
site...that the commercial operator fix any problems caused by their
wide strong digital signal.In this case, the public safety site is the
one with the "wide strong digital signals" causing "harmful
interference".  Further, their signals appears to be "super extremely
clean" and only certain types of receivers have problems in the area.
Also, the public safety user and the other users are where they would be
if the Consensus Plan were implemented.  Also, the problems show up on
channels that are not IM related.Should the public safety operator of a
low site take steps (at their expense) to eliminate the harmful
interference they are causing to other users of the 800MHz band?  If
not, how does one estalish a priority order for the relative importance
of the different users? Eric -----Original Message-----
From: Anderson John-P29444 [mailto:[email-masked]]
Sent: Tuesday, November 04, 2003 9:03 AM
Subject: Re: another interference case

     Can you explain what you mean by your last sentence "Do all
     the things that everyone says about the commercial low height
     sites apply to public safety low height sites too?"

---

From: [email-masked]
Date: Tue, 04 Nov 2003 18:02:59 -0500

------- Original Message --------
   From: "Ron Haraseth" <[email-masked]>
Subject:  Re: another interference case

 Eric,  I'm not sure of the protection rights offered to non-PS users.
They basically fall under the same restrictions of type of operation
depending where they fall in the band.  (They may even have the option
to double their spectrum by moving to 900).  I think they would receive
less, not more potential problems form PS stations after rebanding.As to
the susceptibility of the receivers to intermod etc. after rebanding,
the 800 Symposium last week in Las Vegas included information, highly
quantitative and somewhat technical, that clearly showed statistically a
very clear reduction in potential intermod by segregating the band.
This was based on consultants work in Denver.  I will see if I can get
the PowerPoints that had that information. To pursue what you mention
even further, the pass band of the receivers and the cellular system
transmitters will be shifting away from each other reducing the level of
coupled power transmitted and received in general.  After rebanding, new
equipment will most certainly be even more restrictive in that the bands
are clearly separated (at least for the PS users.).  The business
players shouldn't be concerned about being left in close proximity in
the upper part of the 800 band because they haven't expressed a
significant problem up to this point.  I would suspect this may be
largely due to their expectations of service.  Example, as a cell phone
carrier, I experience dropped calls fairly often, business radio users
expectations are somewhat more critical, but for day to day business,
they typically live with that paradigm.  Obviously, the utilities have a
higher level of expectation of services and it totally dumfounds me why
they would not embrace this rebanding in order to protect themselves in
the future. But for both classic CMRS/businesses and utilities, there is
still an opportunity to reduce the actual interference received from
interleaved cellular operations and near band A/B carrier
interactions. As to the quality of the receivers, you are correct in you
statements. There is good reason to restrict receiver types based at
least for certain geographic area users (higher density areas).Ron
-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Tuesday, November 04, 2003 4:29 PM
Subject: Re: another interference case

What about PS to non PS users?    I'm sure you can see where I'm going
here....Lots of other users that don't fall under the umbrella of public
safety have a large impact on the public's safety.As for the
rebanding......The problem with rebanding isn't really a rebanding.  It
is more of a reorganization of spectrum.  For receiver intermod, the
band involved is defined by the receiver.  Until the strong signals are
moved out of the receiver's front end passband, the problem will still
exist.  Since the receivers currently are designed to cover from 850-869
and the receivers are not going to be changed out, moving the PS to the
bottom of the range and low site commercial to the top will not move the
strong RF out of the receiver's passband. If the FCC is going to make
spectrum management decisions based on a receiver's susceptibility to
interference, the receiver performance should be specified Here is what
I worry about if receiver standards are not specified by the FCC.Bids
responses for a large receiver purchase show up on some contracting
officer's desk.  One bid is for $2800 per radio.  The other is for $449
per radio. Both radios have similar reliability histories. Both radios
can hear -120dBm  at 12dB SINAD.The $2800 radio will work nearly
everywhere.  The $449 radio will only work if there are no other strong
signals below 900MHz.   Since the $449 radio's strong signal performance
is no longer a concern for the person receiving bids, the $449 radio
will be chosen....and the rest of the world will have to deal with
it.Eric