"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