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A different
perspective: The users of the ISM band are basically bound by rules for using the
band which limit harmful interference. There is no precedence or first come first
served nature to the right to operate in the ISM bands. Interference is a given
in the ISM bands and has multiple types of sources: intentional, unintentional,
or incidental radiators. So from my perspective the key definition is not coexistence
but harmful interference. The FCC definition of harmful interference is: “Harmful
interference: Any emission, radiation or induction that endangers the
functioning of a radio navigation service or of other safety services or
seriously degrades, obstructs or repeatedly interrupts a radiocommunications
service operating in accordance with this chapter.” Therefore
my definition of coexistence is: Coexistence
is a condition in which two or more systems may operate in the same general
location, without seriously degrading, obstructing, or repeatedly interrupting each
other. This begs
the question as to what the definition or allowable level of seriously degrading,
obstructing or repeatedly interrupting each other are. But, I believe that the discussion
of these issues is the sole purpose and reason for existence of a “Coexistence
Assurance Document”. The allowable level should be based on engineering judgment
and should be seriously considered during the standards process. I don’t
believe that it is possible to create a definition which will set the allowable
levels or adequately decide this issue; there are simply too many factors to consider.
Regards, Joseph Levy,
P.E. Member, Technical Staff InterDigital Communications, LLC 2 4th Floor,
South Wing (V) 1
631-622-4139 (F) 1
631-622-0100 joseph.levy@xxxxxxxxxxxxxxxx From: Craig Warren
[mailto:cwarren@xxxxxxxxxxxx] That sounds good...some definition of the
impact is a good idea I felt. Craig From:
Shellhammer, Steve [mailto:sshellha@xxxxxxxxxxxx] Craig,
I would say it is not so much as a “minimal” impact but a
“tolerable” impact. The 802.15.2 definition is targeted at
that level, since it says that the application can still perform its
task. Another way of saying it, is that the QoS performance meets an
acceptable level of performance.
Thanks for commenting. Steve From: Craig Warren
[mailto:cwarren@xxxxxxxxxxxx] Hi Steve; Should there be some statement in here
like some minimal impact of the task being performed kind of wording? kindest regards; Craig From: Shellhammer,
Steve [mailto:sshellha@xxxxxxxxxxxx] 802.19 TAG,
Recently with the coexistence discussions regarding 802.11 VHT60 I have been
asked several times for a definition of coexistence. It was pointed out
at the closing EC meeting that one cannot evaluate coexistence without a proper
definition. I explained that the current definition that we have in 802
is the one that was standardized in 802.15.2 several years ago. The
802.15.2 recommended practice was approved by both 802.11 and 802.15.
Yesterday, Bruce Kraemer, the chair of 802.11, asked me if the 802.19 TAG
supported that definition. I have never asked the TAG that question.
So I thought I would send out an email on this question.
The definition in the 802.15.2 recommended practice is, 3.1.2 coexistence: The ability of one system to perform a task in a given shared
environment where other systems have an ability to perform their tasks and may
or may not be using the same set of rules.
I would like to hear feedback on this definition. The TAG could choose to
support this definition or come up with its own definition. There is a
perception that one cannot evaluate the coexistence of two wireless networks
without an agreed upon definition.
If the TAG decides they want to support another definition we could later hold
an email ballot on the definition if making it more formal is useful.
Comments are encouraged. Steve |