RE: stds-80220-eval-criteria: Deplyment for simulations (was FW: Non-member submission from [<shankar@research.att.com>]
Hi again,
For sake of simplicity, and due to the fact that you work under
a lot of assumptions anyway, the shadowing effects can be
included in the path-loss, as a constant supplementary loss.
The scope of the deployment simulation is not to calculate the
exact cost of a deployment, like in a RFI, but to make
comparison between different PHY proposals. And to
understand what is hidden in large coding gains (you know,
nothing is for free).
This relative simple simulation lets you see which is
the PHY data rate /Hz/sq. km.
The other important element for PHY selection is the
resistance to channel models.
Why to hidden the PHY performance / problems, by
taking too many elements together with a lot of
assumptions?
Marianna
-----Original Message-----
From: shankar@research.att.com [mailto:shankar@research.att.com]
Sent: Thursday, July 31, 2003 7:31 PM
To: Marianna Goldhammer; stds-80220-eval-criteria@ieee.org
Subject: RE: stds-80220-eval-criteria: Deplyment for simulations (was FW:
Non-member submission from [<shankar@research.att.com>]
Hi Marianna,
Thanks for the clarification.
I think I understand a little better. The approach you describe:
1) Get rate v. C/NI thresh. information
2) Simulate N and I conditions from 19 cells
3) Use C/NI thresh. to get statistics of
different rates in center cell
4) Process statistics of different rates
to get average PHY rate or some other method
is valid for a link-level simulation. Nothing wrong in that.
In step 2, if you are doing a "full" Monte Carlo type simulation,
you would have multiple discrete points/nodes in all 19 cells,
and evaluate I at each of the nodes in the center. You need
this to capture shadow fade effects accurately.
There are also other ways of simulating using some
kind of aggregate interference based on analysis.
Are you doing a "full" Monte Carlo type
simulation as described above?
- Shankar
-----Original Message-----
From: Marianna Goldhammer [mailto:marianna.goldhammer@alvarion.com]
Sent: Thursday, July 31, 2003 11:40 AM
To: Shankaranarayanan,N K (Shankar); stds-80220-eval-criteria@ieee.org
Subject: RE: stds-80220-eval-criteria: Deplyment for simulations (was
FW: Non-member submission from [<shankar@research.att.com>]
Hi Shankar,
My experience goes with deployment simulations, for the central cell,
with the scope to receive the C/(N+I) distribution in the central cell.
For a given BER and a given modulation+coding combination,
you will have a given C/(N+I) threshold.
So you will be able to evaluate the percentage of the users that can
use a given modulation+coding (you will look always at the max. rate
possible in a given location), and after that you may calculate the
average PHY data rate over the cell. This rate may be used for net
capacity calculation, using traffic models or evaluating the MAC+PHY
efficiency.
Another simulation output will be the combination of PHY rates, and
for voice traffic for example, you will be able to simulate the traffic
using different rates, working with the found percentages and
proportionally combining the rates.
This is the way we simulate.
What do you think?
Marianna
-----Original Message-----
From: shankar@research.att.com [mailto:shankar@research.att.com]
Sent: Thursday, July 31, 2003 5:08 PM
To: Marianna Goldhammer; stds-80220-eval-criteria@ieee.org
Subject: RE: stds-80220-eval-criteria: Deplyment for simulations (was
FW: Non-member submission from [<shankar@research.att.com>]
Dear Marianna,
I agree that CDMA and TDMA are different.
But the main issue would be the kind
of simulation that can be done. Both systems
can still be treated similarly
in the kind of simulation that I
am thinking about.
I am not sure I fully understand the
kind of simulations that you are talking about.
The wrapping discussion applies only if
the details of packet/signal tx/rx are
simulated in the nodes in all the 19 cells.
I suspect your simulation may not
be like this.
There is nothing wrong with analyzing
only the center cell. Wrapping gives you
some simulation efficiency advantage.
But it may not be a valid option in
some cases.
- Shankar
-----Original Message-----
From: Marianna Goldhammer [mailto:marianna.goldhammer@alvarion.com]
Sent: Thursday, July 31, 2003 6:02 AM
To: Klerer Mark; 'stds-80220-eval-criteria@ieee.org';
Shankaranarayanan,N K (Shankar)
Subject: RE: stds-80220-eval-criteria: Deplyment for simulations (was
FW: Non-member submission from [<shankar@research.att.com>]
Dear Shankar,
I think that there is a difference between CDMA and TDMA systems,
related to the required complexity of deployment simulations.
CDMA systems, to improve capacity, use "multi-user detection"
algorithms. TDMA systems do not care about other user detection.
The TDMA companies do not have the needed tools, to perform CDMA like
simulations. Also do not need them.
So I propose to use for TDMA systems the basic 19 cell deployment,
analyzing only the behavior of the center cell.
Kind Regards,
Marianna
-----Original Message-----
From: Klerer Mark [mailto:M.Klerer@flarion.com]
Sent: Wednesday, July 30, 2003 7:07 PM
To: 'stds-80220-eval-criteria@ieee.org'
Subject: stds-80220-eval-criteria: FW: Non-member submission from
[<shankar@research.att.com>]
Forwarded on behalf of a non-member.
-----------------
From: <shankar@research.att.com>
To: <stds-80220-eval-criteria@ieee.org>
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from quoted-printable to 8bit by ruebert.ieee.org
id h6UG19bv021201
As promised at the July meeting, here is
a reference on "hexagonally wrapped"
cellular topologies. This paper is available
on IEEE Explore. This paper talks
about general cases, including the specific
case of 19 cells. The specific case
of 19 cells is also discussed in the
appendix of the 1xEV-DV document in the
drop-box.
If the simulation involves
full simulation of all bases and mobiles
(as opposed to some abstracted cumulative
interference from boundary cells), there
is no difference in complexity or time
between the wrapped and non-wrapped simulations.
The advantage of wrapping is that there are
more (19x times) results and that increases
the statistical efficiency of each run.
The number of cells simulated in the
wrapped case is still 19.
For each receiver, the transmitter position
may get transformed to another "wrapped" position
such that every receiver appears to have
two tiers of 6+12=18 interferers around it.
As discussed in the meeting, there
may be subtle issues if the relative positions
of the mobiles/bases have some
complex inter-dependencies.
The question to ask is: If a transmitter T1
appears at one place for receiver R1, and
appears to be at another place for receiver R2,
(at no point will any one receiver see multiple
signals from T1), does that affect R1, R2,
or some third-party R3 that is trying to
manage multiple things. It may mess up some kind
of referred/derived topology map if
R2 were to later communicate to R1 about its
perceived location of T1.
By the way, note that 19 is a prime number.
If the reuse pattern involves a cluster
of 3 or 4 or 7 cells, then there is an
issue of the pattern not repeating itself.
- N. K. Shankar
=============
Symmetric cellular network embeddings on a torus
Iridon, M. Matula, D.W.
This paper appears in: Computer Communications and Networks, 1998.
Proceedings. 7th International Conference on Meeting Date: 10/12/1998
-10/15/1998 Publication Date: 12-15 Oct 1998
Location: Lafayette, LA , USA
On page(s): 732-736
References Cited: 9
IEEE Catalog Number: 98EX226
Number of Pages: xxii+929
INSPEC Accession Number: 6220023
------------------------------------------------------------------------
Abstract:
Infinite planar cellular networks are embedded on a torus to obtain a
symmetric regular finite network sample region for performance analysis.
We show that a "hexagonal wrap" toroidal embedding preserves
translational and rotational symmetry on all three axes of a hexagonal
lattice and is preferable to a "Cartesian wrap" embedding. Hexagonal
tilings and embeddings are obtained for all rhombic tile sizes. Certain
tilings are shown to provide modular based neighbor addressing schemes
that simplify distributed channel assignment algorithms. Hierarchical
"hexagons within a hexagon" tilings are illustrated with the large
hexagon exhibiting the sample repeat and comprising a multiplicity of
channel frequency repeat small hexagonal the clusters. The symmetric
hexagonal sample region repeat embeddings are noted to be useful for
probabilistic analysis of high utilization channel assignment
performance both theoretically and by simulation
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