RE: stds-80220-requirements: suggestion to modify section 4.2.3 in802.20 requirements Rev 8b
Hi Mike,
Thanks for your comments. I have noticed that section 4.2.3 is still marked
as an open issue in Rev. 8b, and it is also one of the items on the schedule
that John has sent out a few weeks ago.
During the meeting in Singapore, Jin-Weon Chang has presented a contribution
(C802.20-03/77, jointly by DS Park & Joseph Cleveland) on the delay spread
profiles for mobile channels. In some of the channel models that were
specified by ITU, 3GPP or COST 259, the delay spread can be larger than 10
microseconds. Thus, it may be too limited if the future 802.20 system can
only work in channel environments that have delay spreads of 5 microseconds
or less.
The suggestion was to have a high-level requirement that would ensure the
system could perform satisfactorily in the mobile channel environments, with
a high enough probability, without mentioning any parameter related to the
channel models.
Best regards,
Anna.
-----Original Message-----
From: Michael Youssefmir [mailto:mike@arraycomm.com]
Sent: Monday, October 27, 2003 4:52 PM
To: Lai-King Tee
Cc: stds-80220-requirements@ieee.org; Michael Youssefmir
Subject: Re: stds-80220-requirements: suggestion to modify section 4.2.3 in
802.20 requirements Rev 8b
Hi Anna,
My feeling is that the group spent considerable time in discussing
the text for this section before deciding on the text:
"The system should support a delay spread of at least 5 micro-seconds."
By adding the 90% link reliability, I understand that you are attempting
to strengthen this requirement. However, I am afraid that specifying the
link reliability by itself is difficult because it naturally depends
on the channels models employed and we are not specifying these in the
requirements document. At a high level 5 micro-seconds is enough of
an indication to the evaluation group and they will fill in the details
of how well proposals should stack up statistically against this
requirement and what statistical channel model to use. So I propose
that we leave this section as is and not reopen the subject unless we
absolutely must.
Mike
On Fri, Oct 24, 2003 at 03:45:04PM -0700, Lai-King Tee wrote:
>
>
>
> Dear all,
>
> The following is a suggestion to modify the last statement in section
4.2.3,
> Performance Under Mobility & Delay spread:
>
> Current text: "The system should support a delay spread of at least 5
> micro-seconds."
>
> Suggestion for the new text: "The system should support the above channel
> environments with at least 90% link reliability."
>
> Rationale: Based on the presentations on channel models during the
Singapore
> meeting, the delay spread of channels can be much larger than 5
> microseconds. In addition, delay spread is one of the parameters in the
> mobile channel models, there are also other parameters in the channel
model
> that are also important and can affect the performance significantly. The
> capability of the system would be too limited if it is only going to work
in
> channels with delay spread of 5 microseconds.
>
> Best regards,
> Anna.
>