Since we agree that a
consistent approach for all technologies is the way to go,I think now we are just struggling a
bit with the details of how to achieve it.To some extent, this discussion has become as much about the
evaluation process(which is
the purview of another CG) as it is about how to define "network-wide bandwidth". In keeping with
Bob Love's good advice not to dive to deeplyinto the details at the requirements
level, let's trust (or encourage) the EvaluationCG to create a process that provides a
consistent approach to simulating theperformance of the various proposals
within a fixed block size (possibly 5 MHz,which seems to be preferred by many)
and takes into consideration the need
to confinethe transmitted signal
energy, say at the 99% level, to within that fixed block.To calculate throughput in a
specific scenario, the amount of spectrum that
must be allocated to guardbands to meet that 99% level would be subtracted from the total available spectrum prior to multiplying by the calculated spectral
efficiency. I believe the 99% numberguarantees that the variations in
guardband requirements from one technology to the nextwon't be all that significant. It appears
to me that this level of detail should be madea proposal to the Evaluation CG and the
definition of network-wide bandwidth
in theRequirements document could be
left as is, or at least it should
be less detailed than the above.
Best regards,
Joanne
-----Original Message----- From:
owner-stds-80220-requirements@majordomo.ieee.org
[mailto:owner-stds-80220-requirements@majordomo.ieee.org]On Behalf Of
Shively, David Sent: Wednesday, November 19, 2003 8:35
AM To: stds-80220-requirements@ieee.org Subject: RE:
stds-80220-requirements: Spectral Efficiency (4.1.2)
Hi Robert and
Dave,
As Dave
had pointed
out:
---------------------------------
"There seemed last week some confusion about
channelisation, freq. arrangements and the
tabular set of likely spectrum amounts to be
entertained for viable deployments and all coupled
with
the related issue of the evaluation criteria."
-----------------------------------------
I
completely agree. This what I was trying to clarify. It doesn't
make sense to discuss the
adoption of specific spectral efficiency values (e.g.
1 or 2 bps/Hz/sector) without a consistent
way to do the calculation. Of course, this issue also comes up when
performing comparisons
to other technologies.
Best
regards,
David Shively
Cingular Wireless
-----Original Message----- From: Robert D. Love
[mailto:rdlove@nc.rr.com] Sent: Tuesday, November 18, 2003 5:44
PM To: djames@oak-global.com; 'Joanne Wilson'; 'Shively, David';
stds-80220-requirements@ieee.org Subject: Re:
stds-80220-requirements: Spectral Efficiency (4.1.2)
David, you have expressed my concern accurately. As we get into
the detailed evaluation phase it will become more apparent how we must
modify our first set of evaluation criteria to fairly and accurately account
for the range of variability that our candidate technologies exhibit.
Therefore, we should not attempt to drill down too far, nor be too exclusive
of other options as we establish our initial requirements.
Best regards,
Robert D. Love President, LAN Connect Consultants 7105 Leveret
Circle Raleigh, NC 27615 Phone: 919
848-6773 Mobile: 919 810-7816 email: rdlove@ieee.org Fax: 208
978-1187
Yes,
you just beat me to the e-mail on this one. This is really tricky,
rather like determining the length of a piece of string, taking into
account all the possible permutations.
On the
latter point, I did not at last week's meeting also raise publicly the
related question of suitable frequency bands for MBWA (I'd rather we
called it PWDSL, for reasons I gave last week). There are many other
freq bands possible internationally, particularly if the WG can overcome
the tendency to slip back into a mindset over always thinking in terms of
2G/3G spectrum. Last week presentations were restricted to just PCS
and similar bands (after all we were in USA). But there is other
spectrum, and there are many other new operators to emerge (I know, I am
working with some ..).
As if
that is not presenting enough permutations, there is also
the issue we discussed some on what sort of "default" spectrum should
be used for a sensible comparison (or set of such ?) for spec. efficiency.
There seemed last week some confusion about channelisation, freq.
arrangements and the tabular set of likely spectrum amounts to be
entertained for viable deployments and all coupled with the
related issue of the evaluation criteria.
So my
provocative suggestion is - as you imply - that the regulatory aspects be
kept separate here, that the spec efficiency be defined in terms of
"number of carriers deployed" (declared) "and the allocation
block size"; that something like 10 MHz (TDD) or 2 x 5MHz (FDD) be taken
as a baseline usage for all this for the purpose of assessment.
If folk want another higher (or lower) chunk of spectrum, so be
it. In any case, when it comes to evaluation of spec.
efficiency this has to be assessed along with other related
parameters which in turn relate to how one might have to determine
and invoke guard bands or other measures (and here some bands have
modest sharing rather than so-called co-existence issues). Proposals
will clearly have to explain how the spec. efficiency may or may not scale
but may be piecewise incremented (pilots, BCH, correlation and
other considerations etc)
So
I'd agree with your text re "...defining the spectral efficiency
.........
should be done based solely on the technology itself". Of
course that is not the end of it, one has to supply all the other
material, too. So again back to the notion: ".......unique
carriers deployed in the network, including anyrequired spacing
between carriers.
Certainly it seems to make things a lot simpler
if one takes the aggregate DL, UL spec. efficiency /offered traffic rather
than keep carrying the two separately, for there are so many other similar
considerations and permutations for this,
too.
I think Bob Love made a valid point last week in
this respect. There is endless pre-occupation in some quarters (and I can
see why !) over pre-defining exactly how this calculation or that is to be
done and under a thousand permuted scenarios. I think his
valid point was that we should move ahead more firmly, not try to
settle each and every parameter prematurely; many are inter-related,
and in the longer term the requirements, the baseline scenarios,
the eval. criteria, the proposals, the assessment and discussed
possible adjustment constitute a somewhat iterative process. (Bob, tell me
if I misconstrue, please.)
BR,
Dave
-----Original Message----- From:
owner-stds-80220-requirements@majordomo.ieee.org
[mailto:owner-stds-80220-requirements@majordomo.ieee.org] On Behalf
Of Joanne Wilson Sent: 18 November 2003
21:24 To: Shively, David;
stds-80220-requirements@ieee.org Subject: RE:
stds-80220-requirements: Spectral Efficiency
(4.1.2)
Dave,
It seems to me that the guardband
requirements that you mentioned are probably that
which
was needed to meet the spectral mask associated with a
given frequency allocation. Those are
regulatory
matters that are outside of the purview of 802.20 to
set and impossible for us to know without
explicit
knowledge of the market and band of deployment. For
the purpose of defining the spectral
efficiency
of the air interface, I believe it should be
done based solely on the technology itself. In your
example,
you cite cdma2000 as having several different carrier
bandwidths depending on the number of carriers
deployed and the allocation block size.
Based on that, I don't see how one could make a valid
assessment
of cdma2000's spectral
efficiency. The PCS example may just be a deployment issue --
in a 5 MHz
block assignment they were able to deploy three
1.25 MHz carriers with 625 kHz guardbands on the
edges.
A good test case would then be to ask how many
carriers could be deployed in a 10 MHz block
assignment.
My guess (one of the cdma2000 suppliers
or operators could provide a more definitive answer) is
that
they could deploy more than 6 carriers
-- in fact, probably 7 carriers with 625 kHz
guardbands on the
edges. In that case, by your method the
cdma2000 carrier bandwidth would be about 2.14 MHz and
not
2.5 MHz..
All this is to say that I think the guardband
issue, at least with respect to adjacent block
protection,
completely muddies the calculation of the
spectral efficiency for the air
interface.
Regarding UMTS, it was my understanding that
ETSI had a specific work item to modify the
UMTS
air interface so that it could be deployed with
the US PCS allocation in a 5 MHz block size.
Again,
someone from that community can correct me if
that was not the case.
Best regards,
Joanne Wilson
-----Original Message----- From:
owner-stds-80220-requirements@majordomo.ieee.org
[mailto:owner-stds-80220-requirements@majordomo.ieee.org]On Behalf
Of Shively, David Sent: Tuesday, November 18, 2003 1:59
PM To: stds-80220-requirements@ieee.org Subject:
RE: stds-80220-requirements: Spectral Efficiency
(4.1.2)
You are correct that my intention is to define a way to
evaluate spectral efficiency in a consistent
manner.
In the case of cdma2000, the individual
channels can be placed directly adjacent to one another but
there
is still a required guard band on either end
of these channels. For 1900 MHz systems, the guard
band
on each end is typically 625 kHz, for a total
of 1.25 MHz. Thus, for a single cdma2000 carrier the
total
spectrum requirement is 0.625 kHz + 1.25
MHz + 0.625 kHz = 2.5 MHz. For 2 carriers, the
total
spectrum requirement is 3.75 MHz and for 3
carriers the total is 5 MHz. As you noted, the
requirement
may be less at 450 MHz but there is still a
clear requirement for some guard bands
and this would impact
the
calculation of spectral
efficiency.
For UMTS, the chip rate is 3.84 Mcps so the
basic bandwidth requirement is commonly quoted
as
3.84 MHz. This would be the -3 dB bandwidth or,
rather, the equivalent noise bandwidth.
I do not know what you refer to in terms of
modifications for the US PCS bands. The 3GPP
standards
do include the definitions and specifications
for the 5 MHz frequency blocks that are part of the
bandplan
for the US PCS bands. The
3.84 Mcps carrier completely fits into the 5 MHz block since
there is "extra"
space on either
side.
The bottom line is that the spectral
efficiency calculations should be done as consistently as
possible.
From a network operator's perspective, what
interests me is what spectrum efficiency can I get in
a
certain amount of deployed spectrum
(including guard bands).
The alternative approach would be do use only
the carrier bandwidth without any guard bands.
However,
in this case, for example, the UMTS bandwidth
would be 3.84 MHz rather than 5 MHz.
David Shively
-----Original Message----- From: Joanne Wilson
[mailto:joanne@arraycomm.com] Sent: Tuesday, November 18,
2003 12:38 AM To: Shively, David;
stds-80220-requirements@ieee.org Subject: RE:
stds-80220-requirements: Spectral Efficiency
(4.1.2)
Dave,
In principle, I agree with your underlying premise which I
believe is that all proposals should state their
overall
bandwidth requirements in a consistent
way. However, I
don't think your example is quite correct. For
example,
I know that three cdma2000 carriers can be deployed
in less than 2x5 MHz of spectrum (e.g. cdma450
deployments
which I believe are in about 2x4.5 MHz blocks) but
W-CDMA cannot be deployed in less than 2x5
MHz and in fact,
I understand that it had to be modified to be deployable
in the US PCS bands that are multiples of 2x5
MHz block
sizes. So,
I don't believe that the 5 MHz W-CDMA channel bandwidth
includes guardbands.
I believe it would be impossible to determine what would
be the needed guardbands for protection of adjacent block
licensees.
I think it would be make sense to include whatever spacing
would be needed between multiple carriers in a
single
deployment.
If you agree, how about the following
approach?:
"The network wide bandwidth
is the total spectrum in use by the unique carriers deployed
in the network, including any required spacing between
carriers."
Agree?
Best
regards,
Joanne
-----Original Message----- From:
owner-stds-80220-requirements@majordomo.ieee.org
[mailto:owner-stds-80220-requirements@majordomo.ieee.org]On
Behalf Of Shively, David Sent: Monday, November 17,
2003 4:06 PM To:
stds-80220-requirements@ieee.org Subject: RE:
stds-80220-requirements: Spectral Efficiency
(4.1.2)
Regarding these definitions, it should be clearly
understood whether or not guard bands are
accounted for in the calculation of spectral efficiency. For UMTS (W-CDMA), the channel is usually
quoted as being 5 MHz wide. In this
case the guard bands have been included. However,
for cdma2000 1X (and IS-95) the channel is
usually quoted as being 1.25 MHz wide
which does not include the necessary guard bands.
I propose the following:
Network Wide Bandwidth: The network wide
bandwidth is the total spectrum in use by
the unique carriers deployed in the network, including any
required guard bands.
Best regards, David
Shively -----------------------------------------------------------
Dr. David Shively Cingular Wireless 5565 Glenridge
Connector, Mail Stop 950 Atlanta, GA
30342 Phone: 404 236 5909
Mobile: 404 285 5731 FAX: 404 236 5949 email: david.shively@cingular.com pager: dshively@imcingular.com
-----Original Message----- From: Humbert, John J [NTWK SVCS] [mailto:JHumbe01@sprintspectrum.com]
Sent: Monday, November 17, 2003 12:08 PM
To: stds-80220-requirements@ieee.org
Cc: mike@arraycomm.com Subject: stds-80220-requirements: Spectral Efficiency
(4.1.2)
Below is the latest version of the text that was
developed at the Plenary in Albuquerque along with a list of the
open issues for this section.
*
4.1.2 System Spectral Efficiency (b/s/Hz/sector)
* The
system spectral efficiency of the 802.20 air interface shall be
quoted for the case of a three sector baseline configuration
[Footnote 1]. It shall be computed in a loaded multi-cellular
network setting, which shall be simulated based on the methodology
established by the 802.20 evaluation criteria group. It shall
consider among other factors a minimum expected data rate/user
and/or other fairness criteria, and percentage of throughput due
to duplicated information flow. The values shall be quoted on a
b/s/Hz/sector basis. The system spectral efficiency of the 802.20
air interface shall be greater than X b/s/Hz/sector.
* Footnote 1:
Since the base configuration is only required for the purpose of
comparing system spectral efficiency, proposals may submit
deployment models over and beyond the base
configuration.
* Definition:
*
System spectral efficiency - System spectral efficiency is defined
as the ratio of the aggregate throughput (bits/sec) to all users
in the system divided by the network wide bandwidth (Hz) and
divided by the number of sectors in the system.
* Aggregate
Throughput: Aggregate throughput is defined as the total
throughput to all users in the system (user payload only).
* Network Wide
Bandwidth:The network wide bandwidth is the total spectrum in use
by the unique carriers deployed in the network.
* Open items
-
Single value vs. multiple for uplink and downlink - X bits/sec/Hz [note 1
b/s/Hz -or- downlink > 2 b/s/Hz/(cell or sector?) @ 3km/hr
;uplink > 1 b/s/Hz/(cell or sector?) @ 3 km/hr].
- Actual
values of spectral efficiency at higher speeds - TDD/FDD
John J. Humbert 6220
Sprint Parkway Mailstop KSOPHD0504 -
5D276 Overland Park, KS 66251-6118
PCS (816) 210-9611