I doubt anybody can make that perfect grid shown in the white papers.
You just get as close as is reasonable.
When ePMP first came out there was a document describing the two channel
layout vs four channels and it spelled out that there are specific cases
where you are guaranteed to get self interference in a two channel system.
You can switch sync sources in the web GUI.
According to the guys at the ePMP Tour in Albany, the "Front" and "back"
sector designations are strictly informational. Like the "sectorID" in
Canopy. The setting has no actual technical affect, so if you don't
need it as a mnemonic device you can ignore it.
Sriram, that brings up my next question. The channel planning model
for reuse is great for Idealtown, located on a flat plain where one
can permit and build POPs on a tidy rectilinear grid. (This may be
just west of Rolling Meadows). I wonder about the utility of channel
reuse in say, Realtown, where the topology is quite bumpy, forestation
is patchy, and the operator takes what he can get in the way of
locations for POPs. This is pretty much my situation, and probably
plenty of other folks’ too.
I’m trying to think of a broad rule set for channel planning in those
conditions. For instance, I’m planning to expand into an area with
existing structures (silos). In the attached image I’ve modeled
coverage in Radio Mobile with an RSSI of –66dBm or better at the SM,
assuming an ePMP AP/90°sector at power limit for max modulation and
Force (25dBi) SMs (antenna pattern is just an omni for planning
purposes). Max cell radius is 6km. This is over actual topology, of
course, and using a publicly available ground cover (clutter)
database, so it should be a pretty good prediction of which POP gets
best signal to a given location. Each POP has its own color, with some
reuse where it wouldn’t be confusing. (This is RM’s “combined
cartesian” coverage, so there are plenty of locations where more than
one POP can provide better than -66, but the POP with the strongest SS
gets to put its color on the pixel.)
Some of the POPs won’t want a full 4-sector deployment, but many,
probably most, will. Am I better off, generally speaking, with the
recommended 4-channel model, with two of the four channels on each POP
(and the other two channels on the adjacent POP) than I am with the
two channel model? And if so, would I just maintain the same azimuths
for all of the POPs—e.g. channel A always at 0° and 180° and C at 90°
and 270 ° on POPs 1,3, 5…, then channel B always at 0° and 180° and D
at 90°and 270 ° on POPs 2,4,6…? Then maybe we could just leave out
unnecessary AP quadrants on POPs where they weren’t going to do any good.
Is there any reason to try the ABAB reuse model if four channels are
available? Does the necessity of setting Frequency Reuse “Front” and
“Back” go away in the ABCD model—and can anyone explain just what
that’s doing?
Whew.
Oh, yeah—can you just software switch between the GPS timing signal on
the (internal patch or) local GPS port and the signal on the Cat5/6
from a CMM, if you want that kind of redundancy?
*From:*Af [mailto:[email protected]] *On Behalf
Of *Sriram Chaturvedi via Af
*Sent:* Thursday, September 25, 2014 5:45 PM
*To:* That One Guy via Af
*Subject:* Re: [AFMUG] Cambium Newbie Question
Hi,
Yes, the GPS chip comes with an internal patch antenna. The internal
patch antenna is automatically disabled once you connect the external
GPS antenna (and auto enables when you disconnect the external
antenna). If you think the radio itself doesn't have clear LOS to the
sky, then you can use the external antenna and place it elsewhere on
the installation to get better LOS to the sky.
There are a couple of documents on our support site
(https://support.cambiumnetworks.com/files/epmp ) you can read
through that will help answer questions about ABAB deployment using ePMP.
Thanks,
Sriram
------------------------------------------------------------------------
*From:*Af <[email protected]
<mailto:[email protected]>>
on behalf of That One Guy via Af <[email protected] <mailto:[email protected]>>
*Sent:* Thursday, September 25, 2014 4:36 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] Cambium Newbie Question
the APs come with an antenna for GPS, but its never been clear to me
whether there is also an internal patch
On Thu, Sep 25, 2014 at 4:31 PM, Jeremy Grip via Af <[email protected]
<mailto:[email protected]>> wrote:
So would you be able to switch over to the onboard sync remotely? Do
you need an antenna for each AP for using it? Do you think it’s as
precise as using an CMM4 (or SyncPipe Deluxe w/Gig Injector) if not as
robust? If all POPs are sync’d with same Up/Dn ratio and max cell
distance and they’re talking to the same birds, is it pretty much the
same?
*From:*Af [mailto:af-bounces+grip
<mailto:af-bounces%2Bgrip>[email protected]
<mailto:[email protected]>] *On Behalf Of *Adam Moffett via Af
*Sent:* Thursday, September 25, 2014 2:55 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] Cambium Newbie Question
.....also the PMP100 SyncInjector from Packetflux ought to work with
ePMP. You might want the gigE version, but in the real world with a
mix of subscribers at different MCS levels I'm not sure how likely you
are to exceed 100x100.
The CMM4 is a much more rugged beast. It is expensive, but you are
not likely to go back and wish you'd bought the cheap one.
My plan is to hook up the internal GPS and have it available, but also
to provide sync over power. Once you are using GPS sync to re-use
channels it becomes critical that it's always working, so better to
have two timing sources available IMO.
They have built in GPS if youre on a budget, not sure why alot of
people are so die hard against using it
On Thu, Sep 25, 2014 at 12:56 PM, Jeremy Grip via Af <[email protected]
<mailto:[email protected]>> wrote:
I’m looking at ePMP w/channel reuse from a cost-comparison
standpoint. Trying to figure out how much I need to spend on GPS
synch for a 4 AP/ 2 channel cluster. Does it need to be a CMM4? I
will want to be synching multiple POPs…
Jeremy Grip
North Branch Networks,LLC
--
All parts should go together without forcing. You must remember
that the parts you are reassembling were disassembled by you.
Therefore, if you can't get them together again, there must be a
reason. By all means, do not use a hammer. -- IBM maintenance
manual, 1925
--
All parts should go together without forcing. You must remember that
the parts you are reassembling were disassembled by you. Therefore, if
you can't get them together again, there must be a reason. By all
means, do not use a hammer. -- IBM maintenance manual, 1925
