Reza, attached are some of my comments to your
original message.
Regards,
Jim Tomcik
At 06:20 PM
8/1/2003 -0400, Reza Arefi wrote:
Resubmission of the
previous message so that it gets into the archives.
Reza
- -----Original Message-----
- From: owner-stds-80220-coexistence@majordomo.ieee.org [mailto:owner-stds-80220-coexistence@majordomo.ieee.org]On
Behalf Of Reza Arefi
- Sent: Thursday, July 31, 2003 2:22 AM
- To: 802. 20 Coex CG (E-mail)
- Subject: Coexistence CG Kick-off
- Dear Coexistence CG participants,
-
- In its July meeting, 802.20 WG chose to form a Coexistence
Correspondence Group to "study and create a consensus recommendation on
how to address the issues of coexistence of future 802.20 systems with
other wireless technologies deployed in the licensed bands below 3.5 GHz."
- There were two contributions on the issue of coexistence presented to
the WG.
-
- - C802.20-03/72,
by Reza Arefi
- - C802.20-03/61r1,
by Jim Tomcik, Ayman Naguib, and Arak Sutivong
-
- The above two contributions, while consistent on acknowledging the
challenges of the task, presented different views on how to address the
issue within 802.20. While document 72 asked for a Coexistence Task Group
within 802.20 to deal exclusively with the issue in parallel to the air
interface work, document 61r1 suggested that the matter should be studied
by the entire body in series prior to the air interface
work.
Reza, I believe the above statement is somewhat in error.
Document 61r1 suggests that the matter of coexistence should be incorporated
into the standards development process, not necessarily "studied in series
prior to the air interface work." This could be accomplished through
suitable requirements, or evaluation criteria, so that we have some idea how
different technical proposals "stack up" when deployed (for example) adjacent
to current systems.
JW: Please identify the specific coexistence issues that you
believe need to influence the development of
the
air interface specifications for an 802.20 TDD and an 802.20 FDD system,
particularly the AI requirements and evaluation criteria. For systems
operating in licensed spectrum, coexistence challenges usually involve
dissimilar systems. So it could address coexistence of 802.20 TDD and
FDD system with each other. Additionally, co-existence
of adjacent band 802.20 FDD-FDD and adjacent band 802.20 TDD-TDD systems
would be good topics for analysis since those cases are even more probable
than 802.20 TDD-FDD systems in adjacent bands. Coexistence of
802.20 (FDD or TDD) systems with other systems will depend on the
bands where they are deployed and there would most likely be numerous
pairwise
situations that differ from one market (country) to the next.
Also, regarding coexistence in the evaluation
process, are you suggested that system simulations
include simulating other systems in adjacent bands?
I would be interested in understanding in
greater detail what you are proposing so that I can't better
assess
how feasible your proposal would
be.
The goal of the CG is to come up with a recommendation on the best way to
address coexistence within the WG. The coexistence analyses themselves are
outside the scope of the CG and are left to a Coexistence document that 802.20
is likely to produce. Therefore, I see the output of this CG as a concise
document (probably one page) that includes a clear recommendation to the WG
and the rationale behind that recommendation.
Yes, I think this is what we agreed to do. The document
may as you note be 1 page.
- The way I propose to go forward is to have open discussions on the
reflector for a while so that we get a sense of the range of opinions and
the amount of interest in the subject. I will submit to the group a
compilation of all views prior to our first conference call on August 15.
I propose the following four specific topics for discussion on the
reflector so that we stay focused on what we are chartered to do. Please
feel free to choose from the list or suggest other related topics I might
have missed.
I may not be able to make the conference call on August 15
due to other commitments. I will try to get one of our other 802.20
members to attend.
- Given the fact that 802.20 will be deployed in licensed bands, does
802.20 WG need to address coexistence or should the matter be left to the
regulatory regime in each country?
I don't believe this is a strictly regulatory question - we need to
address the effects of a new technology deployed in bands that are currently
being used by other technologies. A good start would be to scope the
problem by defining the targetted bands of operation and mode of operation
anticipated as of this date.
JW: Again, I don't believe
that we should be targeting bands currently used by other fixed or mobile
systems. As soon as we do that the incumbents in the band will rise up
to object. That would move
802.20 into an extremely political situation that
would only detract from progressing the work.
In case the WG chooses to
take up the task, should it create a "Recommended Practice" (one containing
the word "should") or a "Guideline" (one containing the word "may")?
I don't believe a separate document is what's needed for
coexistence. Rather we need to define either requirements or evaluation
criteria so that coexistence is properly considered as 802.20 considers
technology alternatives in building an air interface standard.
JW: Jim, in your presentation you recommended that 802.20 do
something similar to
TSB-84A(1999) - "Licensed
PCS to PCS Interference" which is comparable to a
Recommended
Practice in
IEEE 802 parlence. This is a separate document from the
PCS standards that it
covers. I though we were in agreement that this was an appropriate
approach, that this TSB
was excellent
document of what would be useful for the industry and that 802.20 should
do
something
similar. Since this is not in the scope of out 802.20 PAR, I would
recommend
that the 802.20
Coexistence Group begin developing a PAR for addressing Coexistence
of
802.20
systems.
What are coexistence related issues that need to
be resolved before the work on the air interface could begin?
Some issues to be considered (again, as we develop an air interface) are
the impacts of 802.20 technology deployed adjacent to (in frequency) each
likely existing technology (I'm thinking primarily mobile wireless, satellite,
and GPS). Co-channel interference impacts remains an open
issue.
JW: This is stll ill-defined. "mobile wireless" as
a category is too vague for a coexistence study.
Satellite
and
GPS are different Services (in the ITU's context) than the Mobile Service
where 802.20 would operate
(in licensed bands allocated to the Mobile Service). Coexistence
between different Services, on either a co-channel or adjacent channel basis
is the subject of ITU recommendations and may be included by reference into
the ITU's Table of Allocations. This is way outside of the scope of
802.20. In whatever band
a
802.20 system would be deployed the regulations for that band would include
adherence to whatever sharing requirements that may exist for that specific
spectrum band. Again, this is band specific and can not be
addressed in a general way.
If FDD and TDD
operational bands remain undefined, the work should also take into effect the
impacts of TDD in FDD bands, and Vice Versa.
JW: Two points. Coexistence is not a matter of
TDD - FDD solely. Coexistence can be an issue whenever two dissimilar
systems occupy adjacent bands, whether the are both FDD, both TDD or one TDD
and one FDD. The PCS-to-PCS Interference Document (TSB-84A) addresses
coexistence between pairs of dissimilar FDD systems. All of the PCS
systems are FDD. Impact of TDD in FDD bands? The issue remains the
same, it's doesn't matter whether bands are paired (to support FDD) or
unpaired. The issue is what specifically are in the adjacent
bands.
There may be other issues, but these are the initial
ones I see.
- Should the coexistence work focus on the coexistence of 802.20 TDD and
FDD variants as the primary source of interference problems? Or should it
focus on coexistence with other systems?
Could you elaborate this a little bit? I think 802.20 TDD and FDD
should be considered as interferers, certainly to other systems. In
addition, the opposite effect - existing systems in adjacent channels
impacting 802.20 TDD or FDD is of interest.
JW:
Again, this is an insurmmountable problem because which systems
occupy which bands varies from
country to country. As I stated above, I don't believe that
we should be targeting bands currently in use by existing
systems. That would create a huge
political nightmare for IEEE 802.