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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: higbie.name X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: MN2PR16MB3391.namprd16.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: e7904302-3f82-44f1-8c46-08dc862e95ea X-MS-Exchange-CrossTenant-originalarrivaltime: 06 Jun 2024 13:43:02.1151 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 223bbcd9-6252-452c-afb2-140040991a08 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: F4hbsK8FgLvJWHp2Ygz1LUICUTHrwhlaXdC4xO72pkqz/F+FtojgN6EVRXxplrNyFZTZgEDiisgosMI7O8iANg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR16MB4825 Subject: Re: [Starlink] 300ms Telecommunication Latency and FTL Communication X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 Jun 2024 13:43:05 -0000 Sebastion, I was not providing any knowledge or data on acceptable latency = for video calling. That is not my area of expertise (closest facet of my bu= siness merely involves web site responsiveness and start time for playing a= udio after buffering, both of which are much less sensitive to latency). I = can state that, as a user, I would find 150ms measured ISP latency high, no= t intolerable, but noticeable - video conferencing is more sensitive to lat= ency than pure voice (in my personal opinion, no study I've read on this sp= ecifically), because we watch people's faces for reactions to what we say a= s we're speaking. If there is a noticeable lag there, it disrupts the conve= rsation. On the other hand, the same lag in a pure voice discussion, which = is inherently less synchronous, would not be noticeable.=20 In my prior post, I was using the 150/300 ms figure you provided and saying= that IF that's the max acceptable figure for network latency, THEN that's = already a problem to only hit that as the ISP because each participant also= adds their distance and network delays. For those that are just as quick, = that may be fine. However, assuming there's some form of bell curve distrib= ution on latency, many of these will be longer, and some much longer than w= hat your ISP provides to their customers. Therefore, to ensure a satisfacto= ry experience with the majority of prospective video call participants on o= ther networks, the ISP would need to provide a sufficiently low latency to = accommodate these differences. Otherwise, a significant portion of the call= s would be of poor quality. Obviously, they can't make up for a participant= whose own latency exceeds 300ms, but they should not be the cause of poor = communication with someone at 160ms latency. But that's just reasoning arou= nd your numbers, not data. That said, here are some studies I found that may be helpful: This one includes the 300ms round-trip time, but puts at the extreme outer = range of acceptability: "Defining 'seamlessly connected': user perceptions of operation latency in = cross-device interaction" https://www.sciencedirect.com/science/article/abs/pii/S1071581923000770 "What Are Good Latency & Ping Speeds?" https://www.pingplotter.com/wisdom/article/is-my-connection-good/ A Cisco discussion that supports the 300ms round trip time: "Acceptable Jitter, Latency and Packet Loss for Audio and Video on a WebEx = Meeting" https://community.cisco.com/t5/webex-meetings-and-webex-app/acceptable-jitt= er-latency-and-packet-loss-for-audio-and-video-on/m-p/4301454 These are behind pay walls or require academic credentials, so don't know i= f they are good or not, nor what conclusions they reach - they could even b= e the source of the 150/300ms figure, but I agree with you that seems high:= =20 "A Study of the Effects of Network Latency on Visual Task Performance in Vi= deo Conferencing" https://dl.acm.org/doi/10.1145/3491101.3519678 https://www.academia.edu/98061737/A_Study_of_the_Effects_of_Network_Latency= _on_Visual_Task_Performance_in_Video_Conferencing "Effect of latency on social presence in traditional video conference and V= R conference: a comparative study" https://ieeexplore.ieee.org/document/10402741 "Determination of the latency effects on surgical performance and the accep= table latency levels in telesurgery using the dV-Trainer((r)) simulator" https://pubmed.ncbi.nlm.nih.gov/24671353/ -----Original Message----- From: Sebastian Moeller =20 Sent: Thursday, June 6, 2024 3:22 AM To: Colin_Higbie Cc: starlink@lists.bufferbloat.net Subject: Re: 300ms Telecommunication Latency and FTL Communication Hi Colin, > On 5. Jun 2024, at 19:58, Colin_Higbie wrote: >=20 > Sebastian, >=20 > At 300ms RTT, that would mean the starting point for any communications a= re already at the threshold of unacceptability. [SM] Not according to the ITU (114) mouth-ear delay in ms (so OWDs) 0-200ms: users very satisfied 200-275ms: users satisfied 275-375ms: some users dissatisfied 375-600: many users dissatisfied 600-...: nearly all users dissatisfied So even 150ms OWD still falls within the very satisfied range if the remain= ing delay is not to large... And even if er string two of these users toget= her, we end up with worst case >300ms delay, but that sill only gets us int= o the "some users dissatisfied" which the regulator might find an acceptabl= e trade-off in the context of guaranteed internet access parameters (where = the idea is the 150ms OWD or 300ms RTT is not the target, but the threshold= for being acceptable). My gut feeling is these ranges are not actually measured in a way they are = now interpreted (e.g. when testing transatlantic call delays users likely a= lready had an expectancy of longer delay and simply judges these calls agai= nst a different yard stick). BUT unless I can demonstrate that the original= studies resulting in these numbers are terminally flawed there is little c= hance that I can convince our regulator to take my word vor voice delays ov= er the word of the ITU... so I need different, preferably newer data and fo= cus on probably remote desktop usage as a relative novel use case without m= uch encrusted ideas about acceptable latency... > I would think the strongest argument is that's at best a passable latency= in absolutely perfect conditions, which never exist. "Pleasant" communicat= ion latency is sub-100ms, adding additional travel time to the actual serve= rs involved and processing at each end, the ISP needs to do significantly b= etter than that target to provide some margin for those other sources of la= tency, many controlled by fundamental physics sending the signal over dista= nce. [SM] Personally I agree, yet I am not sure picking a fight over the VoIP nu= mbers is going to be productive, as I have considerably less clout with the= regulator than the ITU... Regards Sebastian