[Sis-csi] Telecon scheduling and request for requirements

[Dave Israel]

Keith,

The 2:30 Eastern time works for me.

Also, the maximum forward link/uplink rate via TDRSS and in the current 
constellation C3I spec is 25 Mbps.

Dave


At 09:33 AM 1/25/2007, Scott, Keith L. wrote:
>========== Telecon scheduling
>
>I apologize for this but we're going to need to reschedule our weekly
>telecons, starting with today's.  Hopefully this will be the last time
>we'll have to do this for a while.  I'll start off by proposing one
>hour earlier on Thursdays (11:30 pacific, 1:30 central, 2:30 eastern).
>Please let me know if this works for you and, if not, what would.  If
>we can't come to consensus quickly we'll wave off this week's telecon,
>but please see below on a request for requirements from the High Rate
>Uplink WG in SLS; I'd like to hash this out over email and get them an
>answer by next week.
>
>========== Request for Requirements from High-Rate Uplink WG
>
>Following up from the Colorado Springs meetings, we've received a
>request for requirements from the High Rate Uplink WG (CWE at
>http://public.ccsds.org/sites/cwe/sls-hru/default.aspx?RootFolder=%2fsi
>tes%2fcwe%2fsls%2dhru%2fPublic%2fCharters&View=%7bED7A93D1%2d1BB1%2d403
>3%2d8432%2dD7382F71947D%7d).  In particular they want to know what
>kinds of uplink rates the cislunar architecture would require.  I think
>that our DOWNLINK requirements should at least cover current shuttle
>and station rates of ~150Mbps, but I don't think we require full
>symmetry on the uplink.
>
>The largest driver for the uplink rate might be crew accommodation of
>live HDTV events, which would be on the order of 5-10Mbps, if they were
>actually provided.  If we had that then we should be able to cover most
>or all of the operational uplink traffic in the margin!  :)  Just as
>another point of reference, 150Mbps of TCP downlink would require
>~2Mbps of TCP ACK traffic.  We also need to remember that in a
>networked world such as we've proposed, one uplink may be serving
>several spacecraft.
>
>In any case, we need to provide them with a number that:
>         1) Is large enough to cover our requirements for a reasonable
>amount of time
>         2) Is not so large that they roll on the floor laughing at us
>
>Regardless of the rate requirement, RFC3819 (Advice for Internet
>Subnetwork Designers) and maybe rfcs RFC3155 (End-to-end Performance
>Implications of Links with Errors) and RFC3366 (Advice to link
>designers on link Automatic Repeat reQuest (ARQ)) seem relevant.
>
>                 --keith
>
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______________________________________________________________
Dave Israel
Leader, Advanced Technology Development Group
Microwave & Communication Systems Branch
NASA Goddard Space Flight Center  Code 567.3
Greenbelt, MD 20771
Phone: (301) 286-5294      Fax:   (301) 286-1769
E-mail: dave.israel at nasa.gov

"Without deviation from the norm, progress is not possible."  -Frank Zappa