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Marianna and Ken,
Unless there is a strong push to make changes to the Simulation Parameters document I would like to keep it closed. If however, there are a large number of people who want to reopen it we can.
In terms of the Coexistence Metric document there does not seem to be a large majority that wants to remove the “Medium Occupancy Metric” but there does seem to be some interest in refining the definition. So I would like to see of we can come to an agreement on any refinement the group wants and then close the Coexistence Metric document also. That way we can focus on the simulation results.
I would suggest that if someone has a specific modification they would like to make to that metric they propose specific wording before the next conference call so we have something concrete to discuss.
In terms of adding an additional throughput metric, which was proposed by Richard on the call, I am fine with that. However, it is not clear to me that it is a substitute for any other metric.
Regards, Steve
From: Mariana
Goldhamer [mailto:marianna.goldhammer@xxxxxxxxxxxx]
Hi Ken,
I have no problem; however I do not know which the process is to re-open the “parameter” document, which has been approved last meeting.
Regards,
Mariana
From: Kenneth Stanwood
[mailto:KStanwood@xxxxxxxxxxxx]
Hi Mariana,
I’d like to see an additional line with offered load of 0 kbps, as well.
Thanks, Ken
From: Mariana
Goldhamer [mailto:marianna.goldhammer@xxxxxxxxxxxx]
Hi Ken,
1. To explicitly address your concern, here is the loading defined by the parameter document (fig. 10 in 07/011r14):
The loading here varies from very low to the max. system capacity when operating alone in the channel.
Regards,
Mariana From: Kenneth Stanwood
[mailto:KStanwood@xxxxxxxxxxxx]
Hi Mariana,
Yes, 802.19 does not design the protocols, but understanding how system work should be factored into how we measure coexistence going forward.
As I said below:
At a minimum, if a throughput metric is used instead, there must be a solid requirement that system A’s impact on the throughput of system B must be simulated for a variety of cases where system A has low or no demand.
It’s not clear to me why such an obvious part of coexistence shouldn’t be measured.
Regards, Ken
From: Mariana
Goldhamer [mailto:marianna.goldhammer@xxxxxxxxxxxx]
Hi Ken,
I think that we do not discuss in this group how the 16h protocols are designed. The only issue which is relevant for 802.19 is the coexistence assessment.
So you can keep your design based on any criteria you want. The metrics, as throughput, relative throughput and hidden nodes will show how your solution behaves. The same about CX-CBP. The parameter document has enough modes to address the situations of concern to you.
It is better to use the time and see the simulation results and to try to understand them and interpret them, instead of conducting discussions on what the “medium occupancy” should be. The aggregate throughput (or relative throughput) of the two systems is an excellent metrics for seeing how flexible their coexistence is. You can try different loading levels. The hidden nodes are an excellent metrics to show how many of the stations will suffer from “harmful” interference.
Regarding the technology itself, it will be chosen by operators based on economic arguments. The coexistence can be first addressed by operator coordination and the protocols will further help. We are all aware that there is no perfect solution. 11y has defined a better energy detection level, however it is far from being perfect because the system shall first work and be economically viable. FCC did not defined what “coexistence” means and actually what we are looking for are just “mitigation” techniques.
Regards, Mariana J From: Kenneth Stanwood
[mailto:KStanwood@xxxxxxxxxxxx]
It’s not clear my reply made it to everyone the first time.
Ken
From: Kenneth Stanwood
[mailto:KStanwood@xxxxxxxxxxxx]
I am still very concerned about the insistence to remove the channel occupancy metric without an appropriate replacement. As was discussed in Denver, it is very valuable to assess how a system implementing one technology may block the use of all or a part of the channel by systems implementing other technologies.
In particular, it is important to see how a technology blocks access by others when the first technology has little or no actual data to send. As we are already aware, any 802.16/WiMAX based technology should be suspect due to the designed operation of unmodified WiMAX systems. Modified WiMAX systems should be required to prove they do not limit access by other technologies under low demand situations within the WiMAX system. NextWave proposed the channel occupancy metric in question because inclusion of that metric in our simulations was key to understanding and modifying the WirelessMAN-UCP protocol in section 6.4 of 802.16h so that it would not excessively block access by similar channel bandwidth 802.11 systems when the 802.16 system had low demand. It is not clear to me that the WirelessMAN-CBP protocol described in section 15 of 802.16h has addressed this problem. Lack of an appropriate metric could hinder the identification and resolution of issues in currently proposed systems and systems likely to be proposed in the future.
I understand the reluctance to accept the metric. At NextWave we had heated internal debate over whether or not to include the metric in our simulations, but when the results came in and the value was overwhelmingly apparent argument ceased.
At a minimum, if a throughput metric is used instead, there must be a solid requirement that system A’s impact on the throughput of system B must be simulated for a variety of cases where system A has low or no demand.
Thanks, Ken
From: Mariana
Goldhamer [mailto:marianna.goldhammer@xxxxxxxxxxxx]
Hi All,
Regarding the yesterday teleconf and the way forward:
1. In my view metrics which do not have a clear interpretation as coexistence criteria shall be omitted, and this is the case of the Medium occupancy where two opposite target criteria were proposed by Paul and Eldad (Paul – 50% of time in case of two collocated systems – was no agreement on this, because is ignoring the antenna separation, powers, modulation, coding, etc.; Eldad 100% or similar occupancy). In addition it is not defined yet what the occupancy is, and we spent 45min. just with a discussion on the different possibilities. This in addition to the time spent in the meeting.
2. I (and probably many others) appreciate the straightforward metrics and criteria proposed by Richard, looking at the relative throughput degradation of the two systems as result of interference. Similar degradation means acceptable coexistence.
3. The hidden nodes are also important, being the exact image of the “harmful interference”. The reception of the signal is directly affected by the hidden nodes. The hidden node statistics is “hidden” in the averaged throughput results, and this is why we need this metrics in addition to the throughput.
4. I think that for the next teconf. we need to invest the time in advancing the CA document itself. We need to discuss the simulation results and agree on the CA text.
5. We spent already more than one year on this issue (Apr. 07 is the date of the first parameter document), in meetings and bi-weekly teleconf. I hope that we will be able to finalize this process asap. We have committed for a much shorter process and the planned resources have gone. Probably the 802.19 guys have also other issues to address.
Regards,
Mariana From: Shellhammer,
Steve [mailto:sshellha@xxxxxxxxxxxx]
Minutes posted on the server,
https://mentor.ieee.org/802.19/file/08/19-08-0002-11-0000-conference-call-minutes.doc
Steve
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