stds-80220-coexistence: Comments: Coexistence CG's Draft Recommendation
Reza, and Others On the List:
Here are some comments on the proposed draft recommendation. I'm
using the version submitted by Reza on October 29. Apologies for
sending out this late, but my dial-in service was not operating last
night from home.
1. Section 2: This section seems to address
coexistence in the sense of task group work to produce a coexistence
document similar in nature to 802.16.2. It does not address the
scope of coexistence within the 802.20 technology selection and ensuing
standard development process. Accordingly, the title should
be changed to "Scope of Coexistence Task Group
Work". For a task group to be chartered, it needs to
have a concise focus, and that should be developing a coexistence
document based on the selected 802.20 technology or technologies.
2. Section 4: Although there is no text shown, this seems to
suggest that minimum performance is an element of the task group's work
in forming guidelines. I think that minimum performance must be
stronger than that, and I would like to see minimum performance in the
802.20 standard, itself. This should be part of the work in PHY
definition.
3. Section 5.2: The third sentence states co-existence is seldom
considered as an air interface evaluation criterion in licensed bands. I
disagree with this statement. Other organization do review
co-existence in evaluating the feasibility of emerging standards
proposals. It is an integral part of the air interface development
process. For example ITU-R has produced M.1225 which details
methods for evaluating technology proposals. The guidelines could
be incorporated into the 802.20 evaluation and proposal
process.
4. Section 5.2: Coexistence and Evaluation Criteria
Coexistence Considerations are an Integral Part of the 802.20 Evaluation
and Technology Selection Process.
Coexistence considerations can have negative impacts on spectral
efficiency if (for example) large guard bands are needed to insure that
already deployed systems are not adversely impacted. This may reduce the
ability of proposed systems to meet the spectral efficiency requirements
currently in debate by the requirements CG.
If, instead 802.20 systems have to coexist by reducing radiated power,
this may also reduce the ability of a proposed technology to meet the
cell-site reuse requirement in the 802.20 project documents.
Different technologies proposed for 802.20 standardization may indeed
have different coexistence characteristics and this fact can influence
whether or not a candidate technology is favored or eventually selected
for the 802.20 standard. I have stated previously that coexistence
needs to be addressed in the Evaluation criteria. I continue to hold that
view.
I believe that our (coex CG's) recommendation to the Evaluation Criteria
CG is that the evaluation criteria needs to contain:
a. a list of several likely incumbent technologies where 802.20
technology proposers will be required to provide coexistence
evaluations. I suggest that we evaluate 802.20 against IS-95,
cdma2000, and WCDMA (both FDD and TDD versions).
b. definition of the detailed coexistence scenarios of interest for
the technologies selected in (a). There is a great deal of previous
work in this area, so this is more of a "selection" from the
possibilities, than a development of new work.
c. definition of canonical rf transmitter/receiver modeling
structures so that coexistence studies may be performed in a coherent
manner (there is much material on this in existence)
d. definition of the coexistence parameters to be reported to
assure that 802.20 systems are deployable, and when deployed, that they
will meet the promised requirements of the PAR without adverse impact to
already deployed systems.
e. a requirement that technology proposers provide an accounting of how
their proposed technology will coexist under the defined conditions, with
an incumbent system.
For example each techoloogy proposer could be required to provide 2 items
for each technology/coexistence scenario; (1) a mapping of Capacity
Degradation vs. Adjacent Channel Interference Ratio (ACIR), and (2) a
mapping of ACIR to center frequency spacing. This will allow
evaluation of the needed guard bands to achieve a required capacity
degradation.
f. A metric for evaluation of different proposals, such as the
number of "carriers" that could be deployed in a given
frequency block.
5. A Missing Section:
We should also include a section on impacts of coexistence on the
eventual 802.20 specification. It will be necessary at some point
to define basic RF parameters and minimum performance for anticipated
deployments of 802.20. These should be included (as far as we know
them) in the written 802.20 standard. As new bands/deployment
possibilities emerge, future amendments to the baseline 802.20
specification may be made to accommodate different regulatory domains and
anticipated deployments. There is ample precedent for this approach
in other 802 working groups.
6. Coexistence and Channel Modeling:
I agree that coexistence work should not have an effect on channel
model selection. The last sentence should read something like this,
though:
"The output of the channel model CG, however, could be used in the
process of selecting propagation models for the specified coexistence
scenarios."
7. Coexistence and Traffic Modeling:
Agreed that there should be no impact here.
Regards,
Jim
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James
D. Tomcik
QUALCOMM,
Incorporated
(858)
658-3231 (Voice)
(619)
890-9537 (Cellular)
From:
San Diego, CA
PGP:
5D0F 93A6 E99D 39D8 B024 0A9B 6361 ACE9 202C C780
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