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RE: stds-80220-requirements: Spectral Efficiency (4.1.2)

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Joanne, and Dave et al:
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 any required 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