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