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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)
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